You might not really think much about your car’s gearbox beyond whether it’s a manual transmission or an automatic one. But if it’s an automatic transmission you’re after, it’s worth considering exactly which type of automatic you want.
Which type? Yes, because in fact, while all automatics change gear for you automatically – as you’d expect – some of them do so in different ways to others.
Most regular automatics are of the ‘torque converter’ type – which means they have conventional cogs in them, just like a normal manual gearbox, but they use a special hydraulic link in place of a clutch which enables them to shift through the gear ratios by themselves.
However, in this article, we’re going to be talking about the CVT automatic gearbox, a slightly less common type of transmission that is nonetheless favoured by some manufacturers because it is cheap to produce and very good for fuel efficiency compared with a conventional automatic transmission.
What Does CVT Stand For, and How Does a CVT Work?
CVT stands for ‘continuously variable transmission’. The name refers to the fact that the gearbox uses an unusual system of pulleys, which are used to vary the gear ratios continuously.
Both pulleys are shaped a little like old-fashioned wooden thread spools – shafts with cones (or ‘sheaves’) on each end, inverted so that they ‘point’ at each other. One pulley is attached to the input shaft – which is turned by the engine. The other is attached to the output shaft, which transmits power to the wheels.
Now imagine the pulleys sitting next to one another within the gearbox casing, and a steel band or chain wrapped around them, linking them together, so that when the input shaft spins, it turns the belt, which turns the output shaft.
This is the clever bit: on each pulley, the sheaves can move toward and away from each other, along the shaft. And if you look at the chain in cross-section, it’s shaped like a V. Therefore, as the pair of sheaves on the input pulley move toward each other, they push the belt outward and away from the shaft.
If, at the same time, the sheaves on the output pulley move away from the other, they will allow the belt to move closer to the shaft, or rest on it. Because the end of the belt on the output pulley now has a much smaller circumference to turn around, it’ll spin the output pulley much faster than the input pulley is turning. Hey presto: gearing.
And because the sheaves on both shafts can move together or apart, to vary the gearing, even if the engine revs stay the same, you can set the engine control unit to pick certain engine speeds that are the most efficient, for any given throttle opening and engine load, and set the gearbox control unit to then adjust the gearing to provide the acceleration the driver is asking for. This effectively provides an infinite number of gear ratios.
Is a CVT Transmission Good or Bad?
As a result of the above, the engine will spend much more time in its efficiency ‘sweet spot’. This means that a CVT vehicle will generally be more fuel efficient than one with a conventional automatic. That makes it ideal for use in applications in which fuel economy is important – for example, hybrid cars or small hatchbacks intended to be cheap to run thanks to low fuel consumption.
CVT gearboxes have one other major advantage: because there are fewer moving parts (just two pulleys and a belt, as opposed to the myriad cogs fitted to more conventional gearboxes) they’re cheaper to build. That means a car manufacturer can save money, either boosting the profit they make on each car, or enabling them to offer the car with a lower list price.
However, CVT gearboxes do have some disadvantages, and they mainly relate to the driving experience. Talking of which...
What’s it Like to Drive a Car with a CVT Gearbox?
It's very easy to drive a car with a CVT gearbox. From a user experience perspective, a CVT gearbox works just like a conventional automatic – you simply start the car, select ‘D’ for ‘Drive’ on a gear selector, and off you go. The one big difference is that CVT gearboxes don’t naturally ‘creep’ when your foot is off the accelerator – that is to say, move forward gently by themselves – but many manufacturers have engineered in that characteristic so that they better mimic the traditional automatic gearboxes people are used to.
On the move, CVT gearboxes feel very smooth compared with a traditional automatic transmission. That’s because there’s no “stepped” gearchange – acceleration is seamless, instead of coming in waves. (That said, some CVT gearboxes have had steps engineered in, preset shift points designed to make them feel more like traditional gear ratios).
One of the biggest disadvantages is that it feels a little unnatural to drive a car with a CVT gearbox, because a CVT is designed to hold the engine revs at a certain point, where the engine is working at its most efficient. What this means in practice is that the car's engine revs don’t rise and fall repeatedly as the car accelerates, as you might be used to, but stay the same – and that can feel quite odd if you’re not used to it.
It can also make the car quite loud. This is because most CVT gearboxes hold the engine at about half-way up the rev range when accelerating – that’s where the best trade-off between acceleration and efficiency can be found.
The trouble is, this can create quite a bit of engine noise – and because the sound is constant, it can be more noticeable (and more invasive) than the peaks and troughs of noise you get with normal gearboxes.
Why Does a CVT Gearbox Whine?
The motion of the steel belt around the pulleys does create a sound – a high-pitched whine that changes in frequency as the car accelerates.
Having said that, with most modern CVT gearboxes you can’t actually hear this from inside the car. That’s because manufacturers have spent a lot of time damping out the sound to make sure you don’t hear it.
So if you’re driving a modern car with a CVT gearbox and you can hear it whining, it suggests there’s actually a problem with the gearbox – it may need the fluid topping up or changing, or there may be something else at fault.
Can You Tow with a CVT Gearbox?
In the early days of CVTs, they were not recommended for towing, because the belts and pulleys weren’t very strong, and towing could put an additional strain on the gearbox that could cause damage.
However, these days, CVTs are much stronger than they used to be, with the result that towing with one isn’t usually an issue. Of course, one should always observe a manufacturer’s recommended guidelines for any car.
Three Great Cars that have a CVT Gearbox
Toyota Yaris
The latest Toyota Yaris won European Car of the Year in 2021; spend a few minutes with it, and it isn’t hard to see why. It looks unlike any other small car on the market today from the outside, while on the inside there’s a solidly built and smartly styled interior.
Under the bonnet, all Yarises feature a hybrid powertrain, so it’s no surprise that they also have a CVT gearbox. And clever calibration means that Toyota’s managed to dial out the worst of the engine noise a CVT would normally bring with it.
The Yaris feels good to drive, too, and it’s remarkably economical – in fact, it’s one of the most fuel-efficient cars on sale in the UK today. And with Toyota’s excellent warranty offer, of up to 10 years, it’s likely to be a reliable buy too.
Read our full Toyota Yaris expert review
Nissan Qashqai
Choose an automatic version of the Nissan Qashqai and you’ll be getting a CVT gearbox in your new car (although you wouldn’t know it, as Nissan badges its CVT gearboxes ‘Xtronic’).
The latest Qashqai is a great car, too; robustly built, practical, easy to use, and with a satisfying blend of ride and handling that makes it a very pleasant and hassle-free thing to get around in.
And while the automatic version suffers from the same trait as many a CVT-equipped car – which is to say, it emits quite a bit of engine noise under hard acceleration – it’s still smooth, seamless, and a doddle to drive the rest of the time.
Read our full Nissan Qashqai expert review
Lexus ES
Like the Yaris, the Lexus ES is available with 10 years’ worth of warranty – something none of its luxury rivals can match. And while most are more involving to drive, the ES instead majors on comfort and solid build quality.
It’s also great value, with prices coming in lower than rivals’. It’s generously equipped and feels upmarket inside, too. And with a hybrid powertrain, the ES’s fuel economy is impressive.
What’s more, with copious amounts of sound deadening, the ES only really becomes raucous when you push it hard; the rest of the time the engine is blissfully quiet, which makes it a very relaxing way to get around.