Here’s the latest reader question, along with my reply!
Chaz asks: My dad has given up on Subaru because of their insistence on using CVT transmissions. Since you are my car “sensei” I was wondering how you felt about these relatively new transmissions.
My reply: CVTs – continuously variable transmissions – have been in general use for about 20 years now; I know, time flies! They offer an efficiency advantage (manifested as gas mileage) over conventional automatics, which have a fixed number of forward gears (e.g., a six-speed automatic).
The CVT – often described as having just one forward “gear” (e.g., Drive) actually has a continuously – and infinitely – variable number of possible ratios, changing incrementally as required by load on the engine, road speed and so on.
In a fixed-gear automatic (or manual) each gear is optimum for a given load/road speed, but as the car goes faster – or slows down – or the load increase (or decreases) the transmission has to jump up (or down) from one gear to the next, missing out on the more optimum “in between” ratios. Also there is the time it takes to shift up or down, and friction losses as gears are engaged – and disengaged.
The CVT does its thing by always maintaining the ideal drive ratio for any condition, without ever having to shift up or down.
Subaru – which has a deserved reputation for unusually thirsty engines given the relatively small size of its engines – needed to improve its MPG numbers, if only for the sake of complying with federal fuel economy mandatory minimums (CAFE). The CVT was a big part of the plan and if you have a look at current Subaru city/highway mileage numbers, you will see they’ve gone up significantly.
Other car brands use CVTs for the same reason.
They’re not bad transmissions – in the sense of being unusually expensive or prone to problems (generally; the early models had some teething issues). But their operating characteristics can be off-putting, especially in a car with an engine that doesn’t make a lot of power.
The tendency is for the CVT to let the engine rev fairly high – close to redline, if you have the pedal to the floor – and then hold the engine at fairly high revs (where it makes whatever power it does make) without the usual decrease in engine RPM (and engine noise) you’d experience with a conventional automatic or manual transmission as it shifts up through its forward gears.
Even in cars that have powerful engines, the car accelerates differently – almost like a jet on take-off roll, with continuous, linear thrust. This is actually a boon because there is no “shift shock” – the coffee-spilling forward/back lurch that occurs in a car with a conventional geared transmission during each upshift, especially at WOT.
But many people prefer the feel of the conventional, geared transmission. Which is why – ironically – many of the latest CVTs are set up to mimic shifts and are even advertised as offering this feature.
But there’s no “shift shock,” even so. Because no changing of gears – just varying of the ratio. A given ratio is simply programmed to be held – and then released – per the programming (or via the manual + and – paddle shift controls these cars often have).
So, it’s ultimately a question of what you prefer.
The CVT gives you mileage as good or even better than a well-shifted manual transmission with the convenience of an automatic. But you may not like the way the CVT behaves vs. the more traditional geared automatic or manual transmission.
Thus, as always, a test drive is in order!
. . .
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Statistically, a CVT has a higher failure rate than most standard multi-speed automatic transmissions.
The main reason is because when a CVT from Jatco or Aisin fails, it cannot be serviced and must be replaced.
Its a dirty little secret that the first-gen Jatco units would almost always have a pump failure when they died, and all the units had torque limitations which were lower than spec’d.
Three manufactures had to extend the warranty on thier CVT’s when failure rates exceeded 22% of shipped units! Nissan is still in court trying to avoid a class-action about the Gen 2 Jatco units in the 2008+ cars.
Also, its known that each CVT model (Jatco or Aisin) had at least one known weakness, the majority of which had to do with the durability of one of the input shafts or its bearings/bushings.
For a number of years there were many of us which knew the units were not very stout but no one would listen.
I totally forgot about that
So glad my gf didn’t get a Rogue, though I wonder how’d she feel in a CX5 instead of her golf?
I don’t dispute that they are probably better. Its the repairs that bother me. By that same token if an automatic transmission goes out its usually thousands to replace too. I’ve heard the CVT’s go bad, cost thousands to replace and after replacement only last about 20k more miles before being replaced again.
Do they still Drone?
Still remember my friend’s Altima Coupe, would of been perfect w/a manual
I have a 2017 Forester XT with a CVT and a 2018 WRX with a 6-speed manual, both cars having essentially the same turbocharged H-4 engine. The CVT almost always picks the right “gear” in any situation and does it much more quickly/smoothly than I can shift manually; corrections are just a paddle shift away if I don’t agree with what it picked. Assuming it holds up, I rate the CVT as superior to a regular automatic or a manual transmission. But the manual is more fun.
Dad just commented that it doesn’t sound any different than a Buick Dyna-Flo from 70 years ago or a Chevy Power-Glide (pre 1953) or a Chevy Turbo-Glide (57-60) or Packard Ultra-Matic.
I’m sure they are far different and the CVT will get better in time. I get a kick out of dad’s passionate hatred over new things he doesn’t really know too much about.
I will continue driving the best car ever (90-97 Mazda Miata)
British Roadster + Japanese Reliability = BEST CAR EVER
CVT sounds/feels to me like on of those old transmissions that was way low on fluid or else about to die. The thing I didn’t like about the Subaru (okay, just one of the things!) was when you’re cruising along and try to accelerate suddenly, it revs way up and makes a lot of noise for several seconds before finally finding the right “gear”. Even my little piece of crap Chevy does better than that. Generally there’s no shift-shock at all but just the engine rpm change from gear to gear.
BTW, CVT is basically a snowmobile transmission. Snow machines have used them pretty much forever, and those are known for eating belts if you don’t stay on the throttle once you are moving.
I’ve driven my neighbor’s late model Subaru. It only seemed to do the rev way up thing while the engine was cold. Once warmed up it felt like a normal automatic transmission but with more speeds than I’m used to. (My own car has a 3-speed Torqueflite. I think the Subaru CVT mimics a 6-speed automatic.)
As far as eating belts, don’t snowmobiles use rubber transmission belts? I know the old DAF Variomatic (an early automotive CVT) did. It’s my understanding though that modern automotive CVTs use a metal chain instead so that shouldn’t be an issue.
Given that it’s just a couple of hydraulic pulleys and a chain I would think a CVT should be more reliable than the crazy 8, 9, and 10-speed automatics commonly in use today but I don’t know if that is actually the case.
I find 3 speeds to be perfectly adequate for most driving and in any event don’t really see any need for more than 4 speeds in an automatic transmission – starting gear, intermediate/passing gear, cruising gear, and overdrive for freeway speeds.