Tell me about continuously variable transmissions

I suggest the OP drive a few examples to see how they behave. They are not all the same across brands. As for dependability, I haven’t heard about any widespread issues. Subaru is recognized as building a very durable CVT, and I’m sure others are, too.

I have a Subaru with a CVT, and I’m quite pleased with it. Some people complain that cars with CVT trannies act and sound like golf carts. There is some similarity in terms of engine revs going up when you need power and then dropping when you are coasting or loafing along. To me, that’s good, as it means the engine is operating at the most efficient RPM depending on speed and how much power is needed. One thing I really like about my car is RPMs drop way down on the highway. I can cruise at 70 MPH, and the engine is still running under 2,000 RPM.

It IS different, and different doesn’t sit well with some people. To meet CAFE regs, manufacturers are pretty much either adding gears to traditional automatic trannies, or using CVTs, which is like having an infinite number of gears. I would be satisfied with either a 6- or 7-speed automatic or a CVT, but you never have that choice with any one car model. The manufacturer chooses one or the other.

I don’t know how many newish cars you’ve driven, but automatic transmissions have improved a lot since 15 or 20 years ago. I can’t address durability, but certainly in function, new automatic trannies (whether CVT or conventional) are much smoother and smarter than they were 15 years ago. I’ve gone back and forth between stick shifts and automatics several times, and I’ve generally been pleased with cars built since 2010 or so with automatics.

I drove nothing but manual transmission cars until 2009 when I bought a Jeep Patriot with CVT. I hated the car in general, not because of the CVT, but because it wasn’t a manual transmission. I’m back in a Wrangler stick and enjoying driving again.

I have a 2012 Nissan Maxima with a CVT:

–pros:

quiet and very smooth, linear power delivery, very quick to change ratios when you need more juice (especially mid to high RPMs when you’re already going, such as passing on a 2 lane road). For relaxed driving it is great.

–cons:
not much power off the line as it revs up, even though it has a fairly respectable engine (290 HP). I drove an older G35 that has the same engine and similar power rating with a 6 speed auto, and it “felt” much faster. I don’t know if that really means it was though.

CVTs supposedly yield fuel economy savings, but my car is not really great in that area compared to similar cars - 21-22 MPG city, 26-27 HWY.

I don’t love it or hate it - would buy one again if the rest of the vehicle appealed to me.

CVTs are a lot older than 30 years. In 1963 I dated a girl who owned a Dutch car called a Daf (daffodil, I suppose) with a CVT. All she knew about it was that it involved a belt riding up and down a cone. She said it worked well. I never saw it.

You should have a look at Subaru. Most of their cars offer a manual as an option and the WRX has a CVT option with flappy paddles so you can row your own gears when the urge strikes or just push the go pedal to the floor when you don’t.

I’ve owned and driven a CVT equipped Sentra, Altima, Murano, Pathfinder (jeez I seem to be in a rut for Nissan).

For some reason the CVT in the Sentra was the only notable “feel” when I was making a left turn after stopping at a stop light.

One thing I noticed when I first started driving a CVT was that I still worked the gas pedal like it was a typical Automatic. On accelerating from a stop, I pushed down on the gas pedal and increased the pressure to maintain a constant RPM. Then I would drastically back off the pedal when I reached cruising speed. It took me a while to realize that I was driving by ear. The car responded and felt exactly like a typical automatic but the reason it did that was from the way I feathered the gas pedal.

It took me a while to relax back into letting the CVT smooth out the ride with constant torque during acceleration.

Van Doorne’s Aanhangwagen Fabriek.

What specific performance issue are you concerned about? Acceleration? Shift timing? Something else? If the vehicle in question was a high-end performance car, I would say you’d probably want to go with the manual to be able to push the car to its maximum ability, but with a Honda Civic, any performance gain you MIGHT get with a manual is going to be negligible. Although there are no high-performance sport cars with CVT yet, manufacturers like Audi and Lexus are using them in their higher end models without issue.

A test drive will definitely give you an idea of how a CVT drives.

I just switched from a Corolla to a Subaru Impreza, and the CVT is like driving on a cloud. (It has the aforementioned flappy paddles but I would only use them to remain slow on a long/steep hill.) Going up a hill – smooth as glass. Seriously, I feel like a hovercraft. The only problem is I start going faster than I realize because it’s so smooth.

CVT for cars have been around for 30 years. They’ve been used in farm equipment much longer. What kept them out of cars was a hp limit on the drive belt. Engineering caught up with that limitation.

modern automatics are now 6-9 speed units that shift very smoothly and keep the transmission in a narrow power band.

The decision should fall on reliability and cost of a rebuild. I know some of the CVT’s are very expensive to overhaul but so are some “regular” automatics. It is one of the few products where I would consider an extended warranty depending on the cost of repair.

No Lexus model uses a belt-type CVT that I am aware of, Lexus hybrid models use Toyota’s hybrid synergy drive system which is functions like a CVT but is mechanically completely different from the belt-type CVTs used by Nissan and Subaru.

Audis with CVTs are unreliable heaps of garbage.

However since all Audis are unreliable heaps of garbage, it’s not clear why anyone would expect an Audi with a CVT to be any different, so this largely goes unoticed.

My wife’s 2011 Nissan Altima has a CVT transmission. It takes a little getting use to not feeling the shifts. Otherwise it’s fine. I heard that Nissan is soon going to have a mode where it feels like the transmission is shifting so people feel more comfortable with it. You can already ‘manually’ shift through the gears.

Many cars are coming out with 6, 7, 8, and even 9-speed automatics. That’s a lot of shifting! Seems to me that the CVT would make more sense than adding more and more gears.

One thing at least with the Subaru ones (I don’t know about the others) is the CVT transmissions actually have a fairly intensive maintenance schedule, at least by modern car standards. It calls for fluid changes every 30k miles and from what I understand they’re fairly expensive compared to a conventional automatic flush, although that may be something that comes down in price as CVT’s become more common.

(At least that’s how I justified buying the stick version even though the CVT gets a little bit better mileage.)

even modern CVTs are input torque-limited. Nobody seems to have come up with a design that can tolerate more than about 270 lb-ft of torque, and Nissan is right there (261 lb-ft) in the Maxima. Those 7- 8- and 9-speed automatics are having to deal with engines producing 400-600 lb-ft of torque.

IIRC they need specialized equipment to change the fluid; there’s no pan and filler tube. At least this was true for the ZF unit Ford used for a few years, and some of the JATCO CVTs used by various manufacturers. Plus the fluid is expensive and trans-specific; belt/pulley designs subject the fluid to intense shearing forces.

No, I’m not a sports car guy. But the difference in performance between my 2000 Accord with a stick, and my wife’s 2009 Accord with an automatic transmission, is really quite noticeable. It’ll stay several seconds longer in a lower gear going up, and you can hear it for awhile being at that point where it almost but doesn’t quite shift to the next gear.

And in general, it’s got that automatic transmission feeling of mushiness when you step on the gas.

And along those lines, it’s got that irritating habit that I’ve experienced with automatics in general, where it feels like the car keeps on giving itself gas for a couple seconds after you take your foot off the gas pedal. (No, I don’t know whether it’s actually doing that, but compared to what happens when you take your foot off the gas and depress the clutch while driving a stick, that’s what it feels like. Your speed doesn’t start tailing off right away like with a stick; it takes a couple seconds more.)

And of course, there’s downshifting. The advantages of a stick over an automatic here need no explanation, I hope.

it is, but it has nothing to do with the transmission type and mostly to do with yours being an older car. Modern cars all have electronic throttle control (ETC or “drive by wire”) and for emissions compliance reasons they “Soft close” the throttle when you let up off of the pedal. letting the throttle snap shut creates a “belch” of pollutants. FWIW my '12 Mustang with a stick shift does the soft throttle close too.

Another question: back in the 1960s, a few manufacturers made dry plate clutch solenoid-activated transmissions. this was a manual transmission that was actuated by a primitive computer. From what i understand, they had a short life (the solenoids would go bad). Seems like a good compromise though-you could shift them manually as well.

That’s what the DSG gearboxes used in a lot of VW group cars are.

From what I understand, they have a big advantage in terms of shift speed over conventional automatics which makes them attractive for high-performance cars, but unlike CVT’s they don’t have a particular efficiency advantage. FWIW, I’ve never really been able to feel much of a difference between driving a DSG and any other modern automatic.

I like Nissan so when I was looking for an Altima I researched them and found that Nissan had recently doubled their factory warranty on their CVTs from 5 years to 10 specifically because of high failure rates. And I found similar complaints from other make’s owners. Automobile CVTs may have existed for 30+ years but they’ve only entered mainstream production in less than the last 10. And I still feel that they are being pushed prematurely and unnecessarily on us because of their modest fuel economy gain.

And yes, 3 MPG is modest*!* On a cross country trip of all highway miles you could figure the dollars you’d save, but in regular city driving you will never notice the difference. Certainly not enough to have my car driven by rubber friction cones… :smiley: