CVT Transmission vs Automatic Transmission

CVT Transmission vs Automatic Transmission

Even if you're not a car enthusiast, you probably have read or heard of CVT transmission. They're somehow different from automatic, even though they both shift gears automatically, a bit weird huh?

In this article, I'll explain the differences between CVT and automatic transmission from the perspective of a driver. I'll also explain why you might want to choose one over the other. I'll focus more on the driving feel rather than the technical differences as the latter has been pretty much discussed to death already. The last thing I want is to bore you to death with automotive jargons like gears, shafts, and splines.

So what is CVT transmission?

A continuously variable transmission also known as CVT is a type of automatic transmission that can change through an infinite number of gear ratios, hence the name continously variable. This is in contrast to a conventional automatic transmission that has a fixed number of gear ratios. In other words, a CVT transmission doesn't have gear at all. Instead it uses a belt and pulley system to "simulate" different gear ratios.

That's it. You can close the site now, you've learned something new today, OR you can continue and read further if you're interested on how CVT transmission works and how it feels to drive.

How does CVT transmission work?

In order to easily visualise how this works in practice. Imagine a bicycle just with a single gear a.k.a single speed. When you pedal faster, the bike goes faster. When you pedal slower, the bike goes slower. However soon you'll realise that climbing uphill is very tiring as your leg now has to pedal heavier. (Technically speaking you need more torque) Soon enough you are now looking at bicycle with multiple gears.

The gears in bicycle are connected to a chain and sprocket system. (A sprocket is a toothed wheel looking thing affixed to your bicycle wheels) When you shift to a lower gear, the chain moves to a smaller sprocket, usually located in the rear wheel. This makes it easier to pedal uphill. When you shift to a higher gear, the chain moves to a larger sprocket. This makes it easier to pedal downhill.

Now with car CVT transmission, the belt and pulley system works in a similar way, with the belt acting as the "chain" and the pulley as the "sprocket". But the main difference is instead of choosing gear ratio by using a combination of sprockets. The pulley in CVT can become bigger or smaller!

When you accelerate, the CVT computer will make sure that the pulley connected to the drive shaft will become smaller. This simulates a lower gear, making it easier for your car to accelerate. When you start to slowly decelerate or ease of on the go-fast pedal, the computer will make that pulley larger. In essence you're now getting a higher gear and thus lower RPM.

I won't go into details how the pulley can change size, or to be more technically accurate, change its diameter, but suffice to say the size of the pulley can vary smoothly from big to small. Because of this you can have pretty much infinite gear ratio.

Automotive manufacturers will usually adjust the gear ratio to suit the car's performance and fuel economy. What they will usually do is choose a gear ratio so that in gentle driving, your car's engine will always have a low RPM e.g 1500-2000 RPM.

This is to ensure that your car is fuel efficient and also quiet. However when you floor the pedal, the gear ratio will change so that your car's engine will always be in the power band e.g 4000 RPM or more. This is to ensure that your car is powerful enough to accelerate quickly.

What it's like to drive cars with CVT transmission?

Now that all sounds nice and dandy. From the explanation above, you might think that CVT is the best thing since sliced bread! However in practice, CVT transmission has a few quirks that might not be to everyone's liking.

The first thing you'll notice is due to the transmission being able to change gear ratios constantly and smoothly, you won't feel any gear shift at all. This is in contrast to a conventional automatic transmission where you'll feel a slight jerk when the transmission shifts gears. (Or big head bobbing jerk when you shift sloppily in manual car)

You also won't hear the classic Fast and Furious "vroooom (getting high pitched) vroooom (getting low pitched)" sound when the transmission shifts gears from high to low RPM. This is because there's no gear to shift in the first place. What you'll hear instead is a constant engine noise and the car accelerating. When CVT was first introduced, many drivers complained that this makes the car seems to have no power and that the engine is droning, which can be true in some cars. Some customers even complained that the car is broken because they can't feel the gear shift.

The second thing and something that many enthusiasts find as deal breaker is the so called "rubber band" effect. This is when you floor the pedal and you want the car to accelerate, but the engine RPM doesn't increase immediately and you feel no power for some time. Instead the RPM will slowly increase as the CVT computer re-adjusts the gear ratio.

This is because behind the scene, and as explained in the previous section, CVT's belt and pulley system needs time for it to change diameter and find the right gear ratio. It's made worse by the fact that CVT transmission is usually paired with small engine that doesn't have much power and torque to begin with, so the CVT needs to work harder to change gear ratios and get that small engine to rev higher.

If you're interested to learn more on how certain CVT behaves in practice with real example, I recommend you to read our 2017 Subaru Impreza 2.0S review. In that article I explained how the CVT in that car behaves in practice and how it feels to drive. In particular, I also explained Subaru's own implementation of CVT which you might find interesting.

In order to alleviate the concerns above, many manufacturers have implemented a "fake" gear shift in their CVT transmission. This is done by programming the CVT computer to simulate a gear shift. Essentially instead of shifting continously between ratios it will shift only between certain pre-programmed gear ratios, often times the ratios programmed are the same as a conventional 6 speed automatic transmission.

Interestingly, some manufacturers (notably Subaru) even program their CVT to simulate a 7 speed automatic transmission! Perhaps in the future we'll see CVT with 10 speed or even 20 speed until people get used to the fact that their car doesn't have any gear at all and the whole purpose of CVT is to have continous / infinite gear ratio...

Are CVT transmissions reliable?

As with many things -- well mechanical things in life -- the answer for this is: it depends. CVT trans these days are dime dozen as many makes and models have them, from Subaru to Honda to Nissan, to Toyota. For Toyota and Lexus especially, CVT is the only transmission you can get if you're getting hybrids. No one is going to argue that Toyota Camry hybrid with its CVT is not reliable.

However the same can't be said for Nissan CVT. In Nissan CVT class action lawsuit of 2022, 2017-2018 model year Nissan Altima and 2018-2019 model year Nissan Sentra, Versa, Versa Note are said "to have a defective continuously variable transmission (“CVT”) which can lead to poor transmission performance or failure." From many forum reports and conversation, it seems like other Nissan models equipped with CVT can also be prone to this failure.

Admittedly this topic deserves its own section however my tip to you is to read review of the car you're interested in and see if there's any mention of CVT problem. If you're buying a used car, make sure to check if the car has been serviced regularly and if the CVT fluid has been changed. Afterall, even traditional torque converter automatic transmission can also fail early if it's been abused or not serviced well.

Should I buy a car with CVT transmission?

If you're looking for a car that's fuel efficient and quiet, then CVT is a good choice. However if you're looking for a car that's fun to drive, then CVT is most likely not for you.

If you are used to driving a car with torque converter automatic transmission, then you might find CVT to be a bit weird and not to your liking. I recommend you to test drive a car with CVT transmission first before you decide to buy one. After all despite my general explanation each manufacturer has their own implementation of CVT and they might behave differently.

If you really don't care for any of it and just want a good economy car to drive, CVT shouldn't be a hurdle. Just get a known reliable car with good warranty or good service history if you're buying used and you're good to go.