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A gel that repairs your worn-out engine? Let me go have a look-see

Hi Baraza,

1) I have a Subaru WRX Impreza with a manual transmission that produces a buzzing noise in Gear 5. What could be the problem?

2) As you might have noticed, I am a diehard Subaru fan and I do not think much about your Evo reviews. I am a keen follower of the time trial competitions and was at the Murang’a TT. The Evos might have won the battle, but they are yet to win the war. I noticed that there were only two branded vehicles competing, one of them a Subaru Impreza N8 with the stickers of a revitalisant. What is that?
Subaru Diehard

Greetings, Subaru Diehard,

1. The buzzing noise is more like a continuous drone, especially at highway speeds, is it not? This sounds as if a synchroniser might be worn out or the gear itself might be chipped. The remedy in such a case is to open up your manual transmission and replace the offending component, be it the gear or synchroniser unit.

2. I did a little research and the results were… well, VERY interesting. This is what I learnt:

a) The manufacturers of the revitalisant have a whole line of products, most of which are in liquid and gel form. If there is a liquid that goes into the engine (oil, transmission fluids, power steering fluid etc), more likely than not, they have their version of it, save for petrol/diesel.

b) They also have other products that they call “revitalisants”, which in essence are “metal conditioners”. What these conditioners do is “heal” scarred metal, like your gear in 1 above. Scratched surfaces can be “revitalised” by the application of a “revitalising” product such as benzoyl peroxide in the control of acne or Candid B cream in getting rid of ringworms.

Now, here is where the plot thickens. Their own blurb says that the revitalising cream (it really is hard to think of it as anything else) will seep into the hairline fractures and scratches on any metal surface, sealing them completely.

It apparently forms a ceramic layer over old metal surfaces, rendering them “as good as new”. Since most metal surfaces damaged in this manner are part of a rubbing, friction-prone pair, the mode of the gel, it is claimed, is to form a kind of hard-pack cement the more heat and pressure is applied, and if it is heat and pressure you seek, you need not look further than the engine. The result is filler material and a coating that effectively restores the metal surface to its factory smoothness.

Derision was not far off. Real petrolheads are a discerning lot and are incredibly difficult to please and/or convince about certain matters. There were those who cried “Heresy!” and dismissed the metal conditioner as a marketing ploy for “magical cement” that has no place in the real world.

Further research reveals that this marketing ploy is nothing short of a cliché, seen before in a million other miracle cures that do not really work, preying on fear and gullibility to generate sales. Then there was the warning notice on the tubes of gel, which tend to come in threes (engine, transmission, and something else, I am not sure what): “Parts, if worn out, will still need replacing.”

Parts will still need replacing. The next question is fairly obvious: if these parts will still need replacing, what is the point of the conditioner?

It turns out that some people blew their engines, then applied the gel thinking that it would restore them. That is not how it works. It does not unblow your engine. It will not fuse broken metal pieces together, nor will it reduce the mileage covered. It repairs distressed surfaces.

The theory is embedded in nanotechnology, which I will not delve into right now for fear of making this column look like the introduction or research notes of a Michael Crichton novel. Nanotech is a field known to many but understood by few. It should, therefore, come as no surprise that the manufacturers chose this word to sell their stuff.

A bit of their history (this should make good reading for Cold War pundits): The discovery of the active agent in their revitalisants came about from a mining operation in Russia in which the engineers noticed that the further down they dug, the “newer” their drill bits became, which was the exact opposite of what they expected.

Apparently, the drill bits were coated in a kind of ceramic material derived from the soil, which kept the bits in a shiny, new condition, whereas in normal digging, the drill bits get eaten away and need replacement every now and then.

This happened very many years ago and some Soviet scientists got interested and started poking into the soil around that particular mine shaft, conveniently located in or near Siberia, in what I believe was a government-sanctioned and KGB-protected undercover experiment lasting several years before the agent (still a secret, clearly, since it goes unnamed) was isolated and put to the test in industrial applications.

This sounds a bit like a flight of fancy, does it not? A legend created by the legend itself in the style of Verbal Kent/Kaiser Soze. Maybe, maybe not, but ask yourself this: Have you ever seen a Russian tank breaking down in any war theatre? Those things are more reliable than the rainfall in Kakamega. In fact, have you seen any old Russian tank? They are all new. There could be some truth to this.

Stepping out of the Ludlum novel and into the real world, the world of testimonies. Of course there are those who will dismiss the revitalisant as a joke, what with the crazy Russian story behind it, the incomprehensible nanotechnology explanation (I do not know if those scientists discovered a colony of nanobots living in the cold Siberian wilderness or what), and the fact that it is cheap for what it does.

Given how much income evangelists generate from mere prayers, imagine how much money Jesus would make if He came back and decided to charge people for resurrections. This is the logic here: If it is actually a miracle cure, why does it not cost more?

There is the flipside of the coin. I have colleagues who have dared to revitalise their engines with the gel and this is what they say. The first one declared “no noticeable difference” and described it as just another oil. Clearly, this person did not follow instructions. You are supposed to add the gel to the oil in your engine. He does not recall any gel, so he is out.

The second one said that his engine actually ran smoother after adding the gel; not just smoother, but noticeably smoother after a distance of about 500km. He is seconded by a third individual.

The fourth one says he, too, had a slightly noisy transmission (like yours in 1 above), with the added benefit of a notchy gear-shift action, but this has since improved dramatically after putting in the gel. There was one who suffered a seized engine following a crankshaft bearing failure, but he swore it had nothing to do with the gel.

I looked each of them straight in the eye for several seconds to determine whether brown Russian envelopes had changed hand, particularly in the case of the last guy. They all seemed legitimate and their claims seemed to hold water (I may have ridden in one or two of these “smoother” vehicles and they are not half bad), so this is where I will conclude my response: I, too, am taking the plunge in the name of research.

I am going to test the revitalisant first week of November. Not that my car actually needs it, though I might have started developing a “slightly notchy” gear-change too. My engine is perfect, if I may brag a little. If the nanotech is nonsense, as some people claim, then I would rather risk my gearbox, which is easier to fix, than my engine.

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Jambo Baraza,
In one of your articles you said: “Nobody ever supercharged a diesel engine.” You were wrong. Check the website Diesel Hub, Supercharged Diesel engines. Also, supercharged and turbocharged are two different things.
J. Jesse (Mzungu)

Yes, Mzungu, I know supercharged and turbocharged are two different things. I have explained this difference too many times for me to make an error in response.

Yes, supercharged diesel engines exist, but these are mostly 2-stroke engines, marine diesels and generators on oil rigs. Some of these engines are V12s with pistons boasting 8-inch bores — not the kind of engine you will find in any car. More importantly, how old are these engines anyway? Few, if any, of the current crop of modern diesel engines used in any application are supercharged.

Part of the logic is this: diesel engines use economy and efficiency as their main selling points. A turbocharger derives its functioning energy from what was otherwise dismissed as waste, increasing its efficiency rating by a wide margin.

A supercharger uses precious engine power to run, which would be self-defeating and in contravention of the conceptual purpose of a diesel engine: efficiency. While providing a substantial boost in power, superchargers are inherently inefficient, more so in comparison to turbos.

The beauty of a diesel engine is that it can take insane boost pressures in the turbochargers with little risk of getting wrecked. Generating more power from a turbocharged diesel engine is relatively simple: keep increasing the boost pressure in the turbo and tweak/replace the injectors with bigger ones.

If you hit a horsepower ceiling with the current set-up, get a bigger turbo, or a second one (or even third, if you are BMW), and even bigger injectors. To begin with, the robust nature of the diesel engine block means it can accommodate a massive horsepower jump with little need for strengthening.

This explains why BMW has an xDrivex30d and xDrivex40d in the X5/X6 line-up. It is the exact same 3.0 6-cylinder turbocharged diesel engine, but in the x40d, it develops a lot more power with little modification.

With the supercharger rendered pointless (now that you can turbocharge the diesel engine endlessly), and it being wasteful in its own way, why would anyone in their right mind want to supercharge a diesel engine?

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Hi Baraza,

I would like to commend you for your good advice to people. I want to buy my first car and am torn between a Toyota Premio, Wish, Voxy, and Nissan X-Trail.

I am an off-road guy who does a lot of travelling upcountry, so I would like a machine that is economically efficient in terms of both fuel and maintenance costs. Secondly, it should manage off-road trips and carry luggage because I am also a farmer. Kindly advise.

Bob

Interesting query we have here because you want to choose between a saloon car, a people carrier, a van, and a crossover, but what you actually need is a pick-up with 4WD. These are five different classes of vehicles.

The saloon car (Premio) will be cheapest to fuel and maintain. The crossover (X-Trail) has running costs not entirely dissimilar to that of a saloon car, itself being based on a saloon car (the Primera), and also has the added benefit of a modicum of off-road talent. Among the crossovers, the X-Trail is actually surprisingly adept at tackling the hard stuff.

None of these cars is exactly ideal for carrying a farmer’s “luggage” (your words, not mine), because in my mind, a farmer’s “luggage” would include tractor parts, ploughs, bags of seeds, fertiliser, animal feed, the animals themselves and/or plants, pesticides, acaricides, fungicides…

You need a pick-up for this kind of “luggage” because, who knows how many bags of seed you will be moving around? Who knows what tractor parts you might be carrying? A diff and a gearbox count as parts, don’t they?

For fuel efficiency, you will need a diesel pick-up. For lower maintenance costs, you will need a diesel pick-up without a turbocharger. For off-road purposes, this diesel pick-up will need to have at least good ground clearance, and possibly 4WD…

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Don’t drive in Neutral gear, it makes no sense at all

Hello Braza,

Thank you very much for your advice on tyre size. It worked perfectly. I have one other question. Somebody advised me to be changing my gear selection to N (Neutral) when going downhill in order to save fuel. Is this true?

Does it have any adverse effect on the vehicle, especially when I change from D to N and vice-versa when the vehicle is in motion?

Please help, and God bless you.

Lisa

Don’t do it, Lisa. There may not be an “adverse effect” per se, but it is risky in that you may bump the lever into R instead of D when going out of N, though this is heavily dependent on the design of the car in question.

Also, it is self-defeating, in that most of the time before going into N most people accelerate hard in D (or whatever gear for a manual transmission) to gain the momentum they think they are preserving in neutral.

If you want to save fuel, drive like this: accelerate gently, but not so slowly as to be a nuisance to me when I come up behind you in a powerful car. Do it within reason.

As a driver, use your discretion as to what “within reason” means. Don’t crawl like an old woman.

Also, don’t stomp the accelerator to the bulk-head, unless under special circumstances… like when stuck at a railway crossing and a freight train is bearing down on you, but this is an unlikely occurrence. We don’t have freight trains any more.

Avoid braking as much as possible, but again within reason. I once said that to someone who offered to drive me from point A to point B, then the joker proceeded to drive into a crowd of people saying “Baraza said not to brake”.

Were it not for the cat-like reactions of the subsequently insanely furious bystanders, there might have been some injuries. No, no, no: brake when necessary, but only when necessary. This is because braking wastes precious energy in the form of momentum, which energy was expended getting up to speed.

Try this: rather than braking hard, try and lose speed with the throttle closed (foot off the accelerator) first, then when you have lost enough momentum and are ready to stop (or the car ahead of you is REALLY close now)… stop.

When going downhill, instead of going into N, simply take your foot off the accelerator. Gravity will still pull your car downhill, so you won’t stop. The compression in the engine will create a retardation effect, so you won’t have to keep braking to prevent your car from behaving like a runaway bicycle. And with modern engines, once the sensors tell that there is no load on the engine, fuel is cut off completely, so you use zero fuel. In neutral, some fuel is used for idling. Which is better?

Economy driving at first seemed fairly obvious to me, but over the nearly-three years of doing this column I have come to realise it is more of an art: not everybody understands it, not everybody can do it, or knows when to do it.

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Dear Baraza,

I have been driving a 1990 Nissan Primera (1838cc) for the past five years. The car has given me no problems at all — until recently, when it started emitting black smoke and guzzling petrol such that I had to ground it. My questions are:

1. What might be the problem, and what is the solution?

2. If I were to replace the engine with a second-hand 1500cc or 1600cc EFI or VVTI one from, which one would you recommend, and how much should I expect to pay for it?

3. What are the things that a layman should look out for when buying a replacement engine?

Luvembe

1. Your car is running rich, very rich, and these are the probable causes: Oxygen sensors, a leak in the intake or exhaust before the oxygen sensors, cracked or disconnected vacuum hoses, faulty fuel system, and clogged fuel lines, among others. The best way to determine the cause is to get an OBD (On Board Diagnostics) scanner that gives you feedback in real time.

2. Be specific. Almost all engines nowadays are EFI (Electronic Fuel Injection), and have some form of variable valve timing. My recommendation would be to buy an engine from that model range (Primera), but newer. It will be easier to install than trying to shoe-horn a Toyota engine into a Nissan engine bay.

3. You can’t. That is why it is advisable you have a reliable and trustworthy mechanic who can help you with such analyses. Either that or someone who knows his way around a car engine. Even I sometimes have to seek help from some of my friends on some matters.

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Hi Baraza,

I have been reading your articles for some time now and I must say I find them interesting.

I would like you to do some research on the Kenyan Traffic Act because I feel police officers have been making their own laws. For instance, who said driving without a driving licence in your car amounts to an offence?

The offence should only apply to those who have never been issued with a driving licence, not those who do not carry it around in person. If you have a licence but have not carried it with you, the law is specific that you should be allowed to produce it within 24 hours at the nearest police station. A lot of drivers continue to be harassed on the road simply because they do not know the provisions of the law.

Finally, I seek your advice on an unrelated matter. Which is the most ideal car to drive between an automatic and a manual one?

Thanks,

Peter Wachira.

I will study the Traffic Act (the full Act, not just the recent Amendments) and do something thorough about it. In the meantime, let me ask you this: if you get into an argument with a traffic policeman, who do you think will win?

If stopped at a road-block and you show signs of being hard-headed (kichwa ngumu) or extremely knowledgeable (mjuaji sana), your day will not go well, I assure you. Most of the time when the police stop you it will be for a legitimate reason. If not, then it is just to let you know that they are watching.

If you start getting argumentative, you are letting them know that you have plenty of time on your hands, and they will help you to occupy this time. Traffic policemen are experts at using time up.

On the second issue: manual or auto. Which one do you prefer? That is the better one. One man’s preferred gearbox could be another man’s accident-in-waiting.

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Dear Baraza,

Please tell me what, in engine sizes and configurations, does the number of valves in an engine mean? I have an example below to illustrate this:

How different is a 2006 6V 2.7-litre Hyundai Tuscon (JM-Japanese version) from a 2007 Toyota Rav-4 with 16V 2.4-litre, VVT-i engine? In terms of maintenance, is there anything peculiar these vehicles require regarding service intervals and requirements, given the different engine configurations?

Many thanks,

Josh.

The number of valves, simply, is the number of valves. There are two types in an engine, according to function: inlet and exhaust. The inlet valves open to allow air into the cylinders. All valves are closed during the compression and power strokes, then the exhaust valves open for the burnt air to be scavenged from the cylinders.

In a nut-shell, the higher the number of valves, the better the engine ‘breathes’ — takes in fresh air and expels exhaust. Still, there are several key constraints, one of which is cylinder head design and the increase in number of moving parts (increases friction and rotating inertia moments of the new masses). So sometimes instead of having many valves it might be better to make the few bigger.

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Hello Baraza,

Your article on hydro cars was a thriller. I’d like to share what seems like a rare find. I read about a Swiss inventor who’s patented square pistons for reciprocating engines… with reason.

Yes, you heard me right. They’re true squares, viewed from top. The square profile enables the piston to tilt with the rod on strokes, eliminating the gudgeon pin. A lighter reciprocating assembly is created by directly welding the piston to the rod or by forging one compact assembly.

Reciprocating masses reduced mean a harder revving, more powerful engine. I did a paper model of it and found it true. It can work. The problem was designing rings that can seal the wide cavities arising. You may consider getting a paper model of it from me absolutely FREE (I’m gifted in craft!) to see how true this is if you haven’t come across it.

I’ve since tried to look for it on the Internet in vain. But I’m not complaining; even more ambitious engine projects like Kauertz are in books but not online.

Lawrence Mutisya.

The problem with square pistons is that the corners create problems. This is how:

1. Lines of weakness. The high pressures and extreme stress caused by combustion will weaken the engine block along those corners first.

This is also the reason why water and fuel tankers have cylindrical containers rather than the cuboids used to transport TVs and other stuff.

The weight of the water will act on the edges first and weaken the structure. A round container has no definite stress point, so pressure is distributed evenly all over

2. The corners look like potential ‘hot spots’, places where pockets of heat form and these could cause detonation and or pre-ignition.

3. As you mentioned: sealing the corner gaps will not be easy.

4. The rotary engine, though clever, never really managed to oust the reciprocating engine. Lack of torque, high fuel consumption, high oil consumption and frequent replacement of rotor tips made them impractical. Mazda struggled to keep the rotary engine alive with the RX-8 sports car but even they had to give it up as a lost cause.

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Dear Baraza,

I work in Rift Valley and reside in Nairobi’s Eastlands. I have an automatic Toyota Fielder X, 1500cc that has proved very reliable. My only problem with it is that, when it rains, I get stuck all over the place, even on flat surfaces.

I am now thinking of replacing it with a good family car with adequate space for cargo. Which, among, the following, would you recommend: Toyota Noah/Voxy, ‘Nissan E-Trail’, Subaru Forester or Honda CRV? Fuel economy is of utmost importance to me, as is automatic transmission.

Thanks,

Zacheus Karimi.

Cargo Space: There is a five-seat option on the Voxy (two rows of seats instead of three), which leaves an entire warehouse of space where typically the other passenger bench would be. That particular configuration leaves the cross-over cars biting the dust in terms of capacious cargo holds. I don’t even want or need to give figures as proof; it is so obvious.

The Nissan X-trail comes second with 603 litres of space with the rear seats up and 1,773 litres with the seats down. This, however, you did not ask about, which leads me to ask a question of my own: what is a Nissan E-Trail?

The Subaru Forester comes at last place, with 450 litres if you don’t drop the rear seats and 1,660 litres if you do. The Honda CRV, according to my research, was quoted in cubic feet: 37.2 with the seats up and 70.9 with them down.

Further research resulted in this being an astonishing (and frankly unbelievable) 1,053.4 litres with the seats up and 2,008 litres with them down. This places it second, especially if you also remove the middle row of seats in the Voxy. It then turns into a pickup. (All figures quoted are for the latest versions of these cars. Next time be more specific about vintage).

Automatic transmissions: All these vehicles have them. The Subaru and the Nissan X-trail also have CVT options, which I’d encourage you to explore, if only to get more people into the world of CVT. I don’t know about the Nissan E-Trail (if such a thing even exists).

Again, these vehicles have some form or other of 4WD, which some would call AWD (Subaru). It is always on in the five-star Fuji product (stars on the logo, not its overall ranking), the Nissan X-Trail has deselectable 4WD via an electronic system (which turns it into a FWD), the CRV is predominantly front-drive until grip runs out fore then power is sent aft (an adaptive system, you could call it), while the drivetrain configuration of the Nissan E-Trail is unknown because the vehicle itself is unknown.

Fuel economy: All these cars rank somewhere in the 9l/100km zone, which translates to about 11kpl. The van can be thirsty if provoked. A way into even better economy would be to acquire a Forester diesel with a manual gearbox (for the 2013 model such a thing does exist), but then again you say you want an automatic car, so… too bad. Also, Subaru Kenya does not sell diesel Foresters. Given Subaru’s past output, it is highly likely they have never even seen a diesel engine over there.

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Dear Baraza,

I have a Nissan Sunny, B15 2002 which is in a good condition. The problem with the car is that I cannot read the odometer clock because it only shows half the digits. When I start the car in the morning I can barely see the whole mileage, and, as the car warms up, the numbers fade off. What could be the problem?

Titus Musyoka

The problem is that your digital odometer read-out is on the fritz, which is just what you have told me. What you want to know are probable causes.

It is unlikely to be temperature-related because engine heat has to go through a veritable buffer zone before it gets to the odo’. That buffer zone has a plethora of insulators within it (insulator in this case is not necessarily the dressing on heat or electricity-bearing components, but rather is any material that does not conduct heat… or electricity.

The opposite of the word “conductor”, in other words). My guess is a loose connection somewhere. The vibrations from the running engine slowly work loose some tiny little wires that feed the digital read-out, so half of it gets blurry or disappears.

That is my best guess. Whether or not I am right is immaterial here: either way you will have to see an electrical expert to sort you out. It may require pushing a wire back in place, soldering it or maybe replacing the whole readout.

Posted on

The Land Cruiser ‘VX’ beats the Prado on many fronts

Dear Baraza,
I have always wanted to know, what is the difference between a Toyota Land Cruiser Prado and a Toyota Land Cruiser VX based on the usual indicators, that is, on and off road prowess and stability, fuel consumption, availability of spares, purchase price, luggage room, comfort, and so on? Is the Toyota Fortuner and Kluger in the same class?

Mwenda

It is good to be specific, as in really specific, because the Prado also has a VX spec within its range. As does the RAV4. But by VX I take it you mean the full-size SUV flagship (the 100 or the current 200?)

On road: Both the 100 and 200 Series Land Cruisers are so much more stable on road than the Prado (all models from J90 to the current J150 have been wobbly and bouncy with a tendency to head for the bushes or lean dangerously with every small lapse of driver attention).

The VX, with its bigger engine, will also outrun the Prado by a very good margin.

Off-road: The Prado will venture further out owing to its more compact dimensions. The shorter overhangs and smaller wheelbase mean it can conquer obstacles more extreme than the 100/200 can handle. And it does have the full off-road kit and caboodle: low ranger gearbox, locking diffs and superior ground clearance.

Consumption: One has a 4.2-litre inline 6 turbo diesel, currently a 4.5 turbo diesel V8. The other has been hovering around the 3000cc 4-cylinder area since God was a boy. One is longer and wider and heavier than the other. I think the fuel economy argument is fairly obvious…

Availability of spares: Toyota were so concerned about readers repeatedly (and annoyingly) asking about spares and maintenance that they even opened another showroom in Westlands, which also doubles as a service centre.

How dare you question the availability of spares for one of the most popular and common Toyota models in the country today?

Purchase price: Really, you are asking me this? Between a Prado and a “VX” which one costs more? Honestly?

Luggage room: The “VX” has a bigger boot. If you are referring to human luggage, both will seat seven in comfort (for later models) or “relative” comfort for the earlier ones.

Comfort: Both are very comfortable, but if you are prone to motion sickness, the Prado will make you vomit like nobody’s business because of its marine-level pitching and wobble. Deep-sea sailors would be at home in one.

The Fortuner is one step below the Prado in this hierarchy, with the Kluger in turn looking up to the Fortuner. The “VX” occupies the top rank.

Baraza,

1. What factors should one consider when trying to make sure an old car (say a Peugeot 405 or 504) is as stable as possible, that is, apart from using a stiffer suspension, reduced ground clearance and low profile tyres?

2. What is the use of the front spoiler (the ones on the front bumpers, especially on Subaru’s) other than making the car look beautiful?

3. Apart from driving gently, is there anything one can do to reduce the fuel consumption of a carburettor car such as a Subaru Leone, or a Peugeot 405/504? Can one use the carburettor of a car with a smaller engine? Is this even possible?

1. Make sure the stiffer suspension is mounted or attached to a structurally sound vehicle body. There’s no point in having a fancy suspension system if the shocks are going to poke holes through the fenders. Reduction of ground clearance should also be done carefully: If you lower the front too much, the car will become nose heavy and understeer through corners, or even worse, oversteer at high speed turns due to lack of grip at the rear. If you lower the back too much, the front will suffer from vague and indirect steering, and a speed steering input could become compromised; not understeer exactly, but something very similar.

Finally, make sure the low profile tyres are well and evenly pumped with air. Varying pressures across and along axle lines will lead to wild and unpredictable cockroach-like darting on the road, especially under hard braking.

2. Spoilers create downforce and/or eliminate lift, the opposite of what an aircraft wing does. By pressing the front of the car downwards, cornering grip is improved, eliminating understeer and sharpening steering response. They also act as stabilisers at speed, along with the rear wing and diffuser where available.

3. You can use smaller carburettors but you will very quickly regret your decision. Lack of power does not even begin to describe the scope of your discomfort. I once told people that substituting the standard cylinder head for one of Honda’s CVCC units also works, but getting those heads is a bit of an issue. They were first used in 1975 and are unlikely to still be in existence. You could fashion one though, if you can get the schematics from somewhere, are good at crafts, have a smelter and a lathe at home and a lot of time on your hands.

Changing plugs and/or fuel pumps can also help, but they will create more problems than solve economy issues. You could switch the head to EFI, but you will find out in the process that it would have been a lot easier to just swap the whole engine.

Hi Baraza,

I own a Toyota Prado TZ and here are the issues I have had with it: 1. Since I purchased the car I have been experiencing brake disk jamming problems. I consulted a number of people but no one has been able to help me with this problem. I changed the brake pads and skimmed the brake disks but nothing changed. Another mechanic advised me to change the ball joints, which I did, but the problem persisted.

2. I was advised by one mechanic to install a turbo change-over switch so as to shift the turbo to ON when travelling long distance and OFF when using it locally. I didn’t agree with him. What is your advice on this; if I install it will it affect my engine in the long run?

PS: I totally agree with the point that the Prado is a bit wobbly car but it is a beast on the road.

1. The problem is called binding. Are the front discs or rear discs affected? If it is the rear, the tension in the hand brake cable could be too high and needs loosening a bit. For all brakes, another cure you could try is take the top off your fluid reservoir and make sure you have something to tap the fluid in then push the piston in the cylinder back in then pump it out not too far and push it back, repeat until it slides back easily.

2. That mechanic is just increasing your expenditure for no good reason. What good will the turbo do when off? If you don’t want to boost pressure acting in your engine just keep your engine revs low. Installing extra hardware is simply providing more scope for things to go wrong in your car.

JM,

I own a Toyota Ipsum 240i 2003 model. The car’s manual indicates a fuel consumption rate of 12 kpl but I have done several experiments and I have only managed to get between 10.3 – 10.6 kpl driving within Nairobi town. Do you think the car might have a problem? I’m a very gentle driver, driving at an average speed of 60 km/h. There are theories that speeds of between 90 to 120 km/h are fuel efficient and that below 90 and above 120, you are being fuel inefficient. What is your take on this?

How does this car compare to a Noah/Voxy and a Subaru Forester both non-turbo and turbo in terms of fuel consumption? What is your general view of this car?

Patrick

What the car’s manual refers to is called the “combined cycle”, that is, for both city and highway use. Your test was limited to town use only. The car does not have a problem, try it on the open road and you should see about 14 or even 15 kpl (at 100 km/h).

That speeds thing is not a theory, it is true. Most cars would comfortably do this speed in top gear, and top gear allows for maximum speed with minimum engine revs.

The actual figure varies between car models and could go as low as 60 km/h (for a Maruti Omni), but the common factor is that the transmission should be in top gear. Doing 90 km/h in second or 100 km/h in third is not efficient either.

Comparison with the Noah/Voxy and the Subaru Forester: It depends on how you drive, but the overall economy figure in litres per 100 km for the Ipsum should be lower than the figures for the other two (that is, it has better economy).

Generally, it is a good family car, but it shares one tendency with some Nissans (B15 and Wingroad) and the old Legacy B4 saloon: the car ages really fast if you are not gentle with it.

Baraza,

I am looking forward to acquiring a 4WD car. I am not sure of the best bet between a Kluger, Tribeca, Vigo (Hilux double cab), an old Land Cruiser VX, and a Mitsubishi double cab. The vehicle is intended for family use’ like travelling upcountry, and carrying light luggage.

Njiru

For a large family, the VX will accommodate up to eight people. The rest can handle only five, except the Tribeca, which is second with seven available human-shaped slots.

Luggage capacity is a scrum between the double cabs, then (surprise, surprise) the Tribeca (with the seats lowered). This is because of the Land Cruiser’s eight seats, none completely disappear like they do in the Subaru, and the high loading level is cumbersome if you are dealing with something very heavy.

My pick would be the VX, but ignore this, it is not for any sensible reason; it is because I prefer its looks to the Tribeca, which is the wise man’s choice here.

Hi Baraza,

I am currently in the market for a car, my 1996 Primera, imported in 2003, has given me faithful service but I feel it is time to move on. I am currently looking at the Toyota Avensis for saloon duty and a 2.4-litre Harrier 4WD for non-saloon duty (a bit of off road, not bundu bashing). And here I also include the Lexus RX300. Now to the questions.

1. Is there a major difference between the hatchback Avensis and the Sedan Avensis apart from the obvious shape thing?

2. I have been told that the 2.4-litre engines on the Avensis are unreliable is that true? A

3. Is there a big difference between a 2.4-litre Harrier 4WD and a Lexus RX 300 4WD in terms of consumption? I know the trim is worlds apart, but someone told me that the 2.4-litre would consume more because it would strain to carry the weight of the car, is this true? And what is its average consumption? (I am not a pedal to the floor type of driver)

4. I saw some very good prices for the Discovery 3 in the UK and I am very tempted. It looks like a very beautiful car, but before I mortgage the wife and kids I would like to know if the reliability issues are true. I am talking about the 2.7-litre diesel.

James

1. No, there are no differences between the “hatchback” and the sedan. Any differences, such as practicality and available space, are directly tied to “the obvious shape thing”. And I think you mean “estate” or “station wagon” for the Avensis, not “hatchback”.

2. Maybe, but what I suspect is that people are afraid of the D4 technology and are trying to make others avoid it too. The Avensis is one of Toyota’s best built cars and has won several awards over the years.

3. 2400cc is capacity enough to handle the Harrier/RX300 body, so you won’t have to strain it to get a modicum of performance. 3000cc is for elitists (like me). Average consumption should be somewhere around 9-10 kpl, especially for calm and sober motorists like you.

4. The 2.7 diesel now suffers from what you have just described in your third question; it struggles to lug all that weight around. The Disco 3’s double chassis adds an elephant’s worth of weight to the car and the 2.7 needs a bit of wringing before it goes anywhere. Good engine though. Avoid the air suspension. Reliability in this day and age is a non-issue.

Hi Baraza,

Having owned a vehicle for a few months, I’d like to further understand a number of things. The vehicle is a 2004 Toyota Noah. I have been using the tyre pressure (~33 psi) as indicated on the passenger side door frame and noticed that the treads are wearing out evenly. In case I change the tyres with locally available ones of similar size, do I still maintain this pressure?

How does terrain and temperature affect the required pressure?

Secondly, I’ve never changed the suspension since the current ones seem serviceable. Considering the car is Japanese, is there cause to worry?

Lastly, on the engine block, there is a label: “Use Iridium spark plugs only”. Is there any benefit to this apart from longevity?

Keep using the 33 psi. Terrain does play a part (deflate the tyres to 15 psi when driving on soft sand, for example), but temperature differences do not affect the tyre pressure that much.

That 33 psi is the manufacturers optimum figure, and gives an allowance for expansion or contraction without adversely affecting tyre performance depending on ambient temperature.

About suspension, if the car does not track straight, wobbles a bit or feels unstable in any way, you can worry. If the vehicle’s stance/posture is even and driving it does not arouse suspicions, then you’re fine.

On the iridium spark plugs issue, there is also thermodynamic efficiency.

Hi JM,

I am planning to buy my first car and I have always loved Subarus. Would you advice me to go for a 4WD with a turbocharged engine? How is the fuel consumption for such a car? I have heard people say that turbocharged engines are delicate how true is this? Finally, what do spoilers and traction control help with?

David

4WD is advisable when you have high-pressure turbo performance at your disposal. It helps in directional stability. Of course the fuel consumption will be worse that NA (naturally aspirated) and 2WD equivalents, but the driving experience will be worth it (in my book). I myself have said that turbocharged engines require care.

Spoilers help with downforce, which eliminates lift and improves grip and traction. Downforce is the opposite of lift. Lift is the result of Bernoulli’s effect, which is what helps aircraft get off the ground, so reversing that lift creates downforce, which presses the car harder on the ground and makes the tyres grip the road surface better. The spoilers work best at high speed, which is when the ground effects are needed anyway.

Traction control eliminates wheel spin by cutting engine power and/or torque to a spinning wheel. This reduces the chances of wild oversteer and/or understeer, or spinning out. It also saves tyres from damage and in some cars, improves cornering performance. In others, turning the TC off improves lap times but only in the hands of experienced drivers.

 

Posted on

Manual cars may offer more fuel economy than autos

Hi JM,
I have an auto 2002 Forester that I would say is quite economical. My wife bought a five-speed manual 2004 Forester that has nearly the same peak power but is far more economical in terms of fuel consumption.

While I spend a thousand bob to Thika and back to Nairobi, she will spend Sh800. This is something I have tested myself and I know it is not tuning because I take both to Subaru Kenya for diagnostics and service. So, is a manual vehicle more fuel friendly that an auto? And if yes, why?

Yes, and for two main reasons. First is a fact that a manual gearbox allows you to short-shift, that is shift up way earlier than an auto would, like at 1,700rpm from first to second.

With an auto, the computer decides when to shift up or down, so there is a tendency for these engines to operate at higher (and racier) rpms, thus pushing up the fuel consumption.

Second is the clutch. Unless the car has an electronically operated friction clutch, most autos tend to have a power sapping fluid clutch, also called a torque converter.

It does not transmit 100 per cent of the engine torque to the transmission; there is some slippage and thus losses at the clutch. These losses translate into less mechanical efficiency and hence higher fuel consumption.

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Hi,
I wish to enquire about the Toyota Verossa. My friends tell me that I may have problems with it when it comes to spare parts and that I should go for Premio instead. Could you kindly advise me on this with respect to fuel consumption in both cars?

The Verossa and the Premio are not in the same class. Your friends should have referred to Mark II or Mark X, which are all similarly sized.

The Premio is a small, compact saloon with a very economical engine while the Verossa is a mid-sized semi-luxury saloon and may be performance-oriented. The bigger engines mean they cost more to fuel over a given distance compared to the Premio.

On a personal note, I do not like the Verossa’s looks. It featured prominently on my list of ugly cars.

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Hi Baraza,
I am planning to buy a car in January but I am not sure what car I should go for. I will mostly require the car to run work-related errands within the CBD and occasionally outside Nairobi.

With the skyrocketing fuel prices, I am keen on a car that is not “thirsty” but I also do not want something that is small and too girly (IST, Vitz — no offence meant).

I have in mind a Premio, Allion, NZE, Avensis, or a Nissan Primera. I am also torn between buying the car locally (one that has not been used on Kenyan roads) and importing. Kindly advise.

You want a small car? You want economy? And you want something not too girly? And, in the name of nation-building, you also want a locally sold unit? Forget Allion, forget Premio, forget NZE. There is a car that fits the bill exactly, though — Maruti Omni.

It is dirt cheap, even brand-new, it is small but handy (seeing as to how it is a van), and that puny 800cc engine will burn less petrol than anything else on the road, other than a motorcycle.

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Hi Baraza,
On the question about the handbrake sign, highlighted here some time back, it happened to my old model Ipsum too. When the handbrake was disengaged, the light would stay on. When I did a diagnosis, I found that the problem was the brake fluid lid.

Thanks for the heads up, but the lady said performance was also compromised, so my thinking was that the handbrake itself was increasing the load on the engine.

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Hi
I have a 2002 Toyota Vista 4WD with a D-4 VVT-i 2000cc engine. The engine light would go on and off for a while, then stay off for months. I did a diagnosis that yielded “p1653 SCV circuit motor”.

I changed the oxygen sensor and the plugs and cleaned all the speed sensors at the wheels, but there was no improvement.

Now, the car misfires in the morning and produces smoke before attaining the operating temperature. I have also realised its consumption has gone up. I was advised by my mechanic to use synthetic oil for service. What could be the problem and where can I get help?

Mwangi

SCV is the swirl control valve and I think it needs replacing. This is one of the weak points of a D-4 engine. I do not know anybody who can open one up and put it back together. Pole.

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Hallo Baraza,

I drive an automatic 1.6 litre 2002 VW Golf Mark 4 (station wagon). Unfortunately, I have never driven other cars so whenever people ask me about its consumption compared to other vehicles, I am at a loss. Could you please clarify or provide insight into the following issues.

1. What, in your view, is the normal consumption in km/litre for a 1600 cc vehicle (whether Mitsubishi, VW, or Toyota) in peak traffic (Nairobi situation) and on the highway?

2. When I suddenly slow down, like when approaching a bump or something is crossing the road, accelerating afterwards is problematic, the vehicle behaves as if it is in neutral gear. But if you step on the acceleration pad once then release and then step on it again, it picks up well. Please unravel this for me.

3. When driving, mainly on the highway, at gears three to five, should the rev indicator settle at, say, less than 2,000? How should the rev counter ideally behave when driving? Does the consumption of the vehicle change when the rev counter is higher?

Finally, it may be a good idea for you to lead a forum for motorists to exchange experiences. For instance, you can organise a forum for Mitsubishi Galant owners on where they physically meet and share experiences such as how they rectified a particular problem.

Tom

1. In traffic, expect anywhere between five and nine kilometres per litre, depending on the severity of the gridlock. On the highway, anything from 14 kpl upwards is possible, with as much as 24 kpl for a diesel engine of that size.

2. Is your car automatic? If so, then the gearbox is what we call “lethargic” or slow thinking; it takes some time before it realises that it should have geared down by that point. If not, another suspicion could be a jamming throttle pedal, so much so that the first gentle prod does nothing, so releasing and depressing it again resolves the jam, allowing it to move as it should. Just a theory.

3. Ignore the rev counter. How does the car feel and sound? If it stutters, judders, or sounds like it is about to stall, the revs are too low or the road speed is too low for that gear and you should downshift. If the engine sounds belligerent, high strung, “shouty”, or if the needle points towards the red line, shift up or ease off the throttle, you are almost over-revving the car. And yes, at higher rpms (4,000 plus), the fuel consumption is a little bit higher than at mid-level revs (2000-3500 rpm).

Finally, visit www.carbaraza.com to start a discussion topic — physical meetings will call for a venue, an announcement and, knowing Africans, refreshments will be expected. In other words, non-refundable costs. So I prefer the Internet.

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Hi JM,

I am interested in purchasing a mini-van and I am inclined towards a Nissan Serena 1990cc, but everyone I know advises that I should get the Noah instead. I am sorry, but I think Toyotas are a bit over-rated. Would you kindly compare the two vehicles in terms of consumption, road handling, parts, and anything else that you may find useful, especially for female drivers?

Christabellah.

Yeah, the people’s faith and belief in Toyotas is damn near religious in intensity, and for good reason. Count how many cars you see and express the number of Toyotas in that group as a percentage and you will see what I am talking about.

The Serena, if we are to go by reputation, has an ugly ancestry — one of the earlier models (late ’90s) earned the dubious honour of being the slowest accelerating new car on sale (at the time), taking a calendar-filling 19 seconds to clock 100 km/h from rest.

Later versions are, of course, better than that, but the damage has already been done. There is a new version out (2012), but I doubt this is the car you intend to buy.

Consumption should be broadly similar but the Serena may edge the Toyota out slightly, but nothing that cannot be corrected with a small adjustment in driving attitude.

Handling is a mostly redundant characteristic in vans (I do not see you oversteering a Serena on purpose) but maybe the Toyota takes it here.

Parts and service also go to the Toyota; there are plenty around, so mechanics have been practising a lot and dealers bring in spares in droves because of the ready market.

So, against my better judgement, I would say go for the Toyota if you want a cautious approach. Go for the Serena if you have a pioneering spirit; who knows, you might start a fad like someone did with the Galant some years back.

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Hi Baraza,
I am planning to buy a Toyota Cami. Is it friendly to a low -lass earner and does it have different ccs? What are its general advantages and disadvantages? Where would be the best place to buy one?

It is very friendly to a low-class earner — cheap to buy, cheap to run, and will rarely break down (it is also called Daihatsu Terios). I know it is 1300cc, but there could be a 1.5 somewhere in the line-up.

Advantages: It is small and, therefore, easy to park and not too thirsty. It can also do 85 per cent of the off-road tricks that a Land Rover Defender can. Disadvantages: It is bloody uncomfortable, 100 km/h plus on the highway is more dangerous and nerve-wracking than an afternoon as a matador, and the small size means you will be getting pretty intimate with your passengers.

Posted on

Overdrive: Keep it off when overtaking or lugging loads

If there is one thing any columnist tries to avoid, it is repeating oneself. Unfortunately, I will have to do just that this week.

I had talked about overdrive earlier, but reader feedback suggests I left a lot of unsatisfied curiosities out there, so we will have to put aside the happy-go-lucky merry-making of test drives and racing this week and step back into the lecture theatre.

Class is now in session, and the topic today is automotive transmission characteristics in general and two things in particular: the overdrive unit and Continuously Variable Transmissions — close relatives of the typical automatic gearbox.

The Overdrive Unit

This is one of the most misunderstood aspects of automotive transmission systems, especially when coupled to an auto-box.

Let us start with the overdrive unit in a manual transmission car as it is easier to explain away. In some instances, it is used as a standalone gear, just after top (1-2-3-4-O/D).

In such a case, the top gear of a car channels power directly from the clutch past the gearbox to the differential unit, with no gear reduction whatsoever.

With overdrive, what you have is a gear taller than top, in a reverse situation where, instead of gearing down, now the unit gears up the entire powertrain.

The overdrive unit/gear gives the gearbox a higher output speed than input speed (in top gear, both input and output speeds are the same).

It is usually used for cruising in low load situations because it keeps engine speeds low thus saves fuel and reduces wear and tear on the engine.

The other type, used in old British sports cars was the type you engaged or disengaged at will. It provided intermediate gears for the manual transmission, such as third-and-a-half (taller than third but just below fourth).

In those days three-speed and four-speed boxes were all the rage, so the gearing was interstellar at best to cover the high-torque, low-speed demands met by the lower gears and still provide power-sensitive top end zoom in the higher gears.

For the sake of example, let us use third and fourth. Shifting up and down between third and fourth is not only annoying for the driver, but it also impedes smooth progress and affects fuel economy.

An intermediate gear becomes necessary, let us call it third-and-a-half. The only way of getting this gear 3½ without changing your entire gearbox is to use an overdrive for the third gear, giving the intermediate ratio.

This overdrive could also be used for the other gears, even reverse. Nowadays most manual transmissions are six-speed, so the overdrive gear has been rendered unnecessary.

In automatic powertrains, the overdrive unit is a bit more complex. Long ago, it was a selectable position in the auto-stick, P-R-N-D-O, but nowadays, it is electrically activated by a push-button, commonly found on the gear lever itself. For practical purposes, we will look at the overdrive unit in a Volvo car:

The overdrive unit uses an epicyclic gear set, which is in essence a set of gears, one nestled inside the other, almost concentrically, if you will.

It is not entirely dissimilar to the planetary gear set used in most auto-box transmissions, except that it is not so far-reaching and versatile.

When engaged, the driveshaft connects to the carrier gear, the outermost gear set of the epicyclic arrangement.

When the carrier gear turns, the internal gears rotate slightly faster. The innermost gear set is called the sun gear, and it rotates much faster than the outer planetary gears courtesy of the diverse ratios.

The sun gear is the one connected to the drive axles, which turn the wheels of the car. In a nutshell, the sun gear (output) rotates much faster, at higher rpm, than the carrier gear (input).

Pressing the O/D button on the gear lever (turning it on, in this case) sends an electronic signal to a switch located within the transmission that engages the overdrive gear.

The end result is reduced engine speed for a given road speed, which in turn means improved fuel economy and less engine strain. For cars with high torque outputs, this could also mean a higher top speed.

So when to use it? I’ll tell you when NOT to use it. Leave it off when lugging heavy payloads, when going up steep hills, when overtaking or accelerating hard and when off-roading.

In other words, where high torque application is necessary, using overdrive is self-defeating. Also, do not use overdrive when going downhill and depending on engine braking to keep your speed in check.

Engaging it will allow the car to “run away”, seeing that the rev range necessary to provide sufficient compression resistance to slow the car down might correspond to much higher road speeds than anticipated.

Leave it on during ordinary driving, though. The benefits are enormous. However, some people claim that using overdrive when passing slower traffic may boost your speed, but this is only applicable in cars with high torque outputs.

Try that in a Vitz, on a small hill, and you will see dust.

Continuously Variable Transmissions

This is an adaptation of a typical automatic gearbox, and some of you may have across it. Have you ever driven a car with what looks like an auto-box, but vehicular acceleration is not at par with engine revs?

The car may accelerate rapidly but the engine revs stay constant, and those who are keen may have asked: what the…?

No need to curse, it is called a continuously variable transmission, and is the only gearbox you will ever find anywhere with an infinite number of gears.

Such are common in Euro-spec and JDM Nissan road cars: it debuted in the second-generation Primera saloon, and has seen action in the minuscule Micra and of late, the second-generation X-Trail crossover.

Even some Toyota Opa cars have this type of gearbox, and most interestingly, those silly go-karts that scared me half to death in South Africa’s Cape Province depend on this type of transmission too.

This is how it works: Unlike your typical gearbox which sports distinct toothed wheels (cogs or, better yet, actual gears) the CVT setup uses belts and pulleys that vary ratios infinitely between low (first gear, for maximum torque) and high (top gear, for maximum speed) and everything in between, all steplessly, hence the claim of having an infinite number of gears.

The most common type of CVT (and the one we will dwell on today) is the belt-and pulley system. This setup uses two opposing cone-shaped variable-diameter pulleys connected by a chain or metal belt.

One pulley is mated to the engine (input shaft) while the other is attached to the wheels via the driveshaft. Each pulley is made of movable halves.

When the halves move apart, the pulley diameter reduces as the belt slides down the cone faces, and the belt is forced to ride lower.

When the halves move closer, the belt slides up the tapered cones and the pulley diameter increases.

Changing the diameter of the pulleys can be done in indistinct steps, and this varies the transmission’s ratios, i.e. the ratio of the rpm of the input shaft to that of the output shaft, which in essence is what a typical gearbox does.

The only difference is in the other transmission types, this is done in distinct steps: the gears themselves. Think of the CVT the same way as a 10-speed bicycle directs the chain over a number of smaller gears to multiply torque.

To maintain the tension in the belt, as one pulley reduces its diameter, the other increases its own, and all this juggling is what creates the infinite gear ratios.

Making the input shaft pulley diameter as small as possible and the driveshaft pulley as big as possible gives “first gear”: maximum engine revs giving minimum road speed.

With acceleration, the pulleys vary their diameters to optimise the engine speed/road speed relationship, up to a point where the input pulley is big and the output pulley small for lower engine speeds and higher road speeds: that is “top gear plus overdrive”.

All this is made possible through sensors and microprocessors. The CVT, however, sounds odd; if anything, the noises coming from under the hood would suggest a transmission failure of some sort in other powertrain configurations, but it is perfectly normal for a CVT.

Also, the seamless power delivery would give a feeling of lethargy from behind the wheel when in actual fact the CVT can outperform other conventional transmission types. As such, CVT cars are still struggling to find acceptance in society.

To counter this, car manufacturers have had to inculcate some features that are in direct contrast to CVT characteristics, such as the creep feature like you would find in a normal automatic, and “gear simulation”, distinct steps in the transmission progression.

Driving a car with a CVT is a bit disconcerting. Even before the unusual acceleration at constant engine speed, stomping the throttle at take off makes the car sound as though the clutch is slipping or the automatic gearbox is failing: there is more noise than movement as the car adjusts the engine speed and road speed for the most appropriate relationship.

The reliability of CVTs has also been brought into question as they are delicate by nature. However, more robust construction has made them able to handle more powerful engines.

Initially, the CVTs used earlier could not handle more than 100 hp, but the current ones are capable of channelling up to 290 hp (Nissan Altima) to the tyres form the engine.

Just how good is this type of transmission? For starters, it was banned in Formula 1 because it was making the cars too fast(!).

It is also used widely in farm machinery, from tiny garden John Deere tractors to full-scale combine harvesters.

The benefits of a CVT are more usable power, a smoother drive and better fuel economy; though how this works out I don’t know.

The Gen-II Nissan Primera with a CVT returned a mere 23 mpg (7 kpl) from a 2.0 litre 4-cylinder engine. Maybe the economy figures have improved since then.

There are other forms of CVT, such as toroidal, hydrostatic, ratcheting and infinitely variable transmissions, but I doubt if I want to get into all that here and now. Maybe later.

Fun fact: The great scientist Leonardo Da Vinci actually invented the CVT back in 1490. Daf (from the Netherlands) put the first CVT into automobile application in 1958, and only in 1989 did the first US-sold production car have a CVT: the Subaru Justy GL hatchback.