Do CVT transmissions have an actual purpose (gasoline cars not hybrid)? Are they necessary to have them in cars today? Are CVTs any good regardless of the manufacturer? Is it better to have virtual gears rather than actual gears? Are they even getting better fuel economy as compared to a regular automatic transmission? If it's the same fuel economy, are they a waste in cars today?
I’m not a fan. But they do have a small benefit for fuel economy. They are also more compact (which is why Subaru uses them; they need a short transmission unit to fit a longitudinal oriented engine in a small car, and CVT fits better than conventional).
Until Congress repeals CAFE, CVTs are here to stay and will only get more common
Do CVT transmissions have an actual purpose (gasoline cars not hybrid)?
Of course they have a purpose. Without a transmission, cars would have a very limited speed range. The aim of the CVT (and any transmission) is to keep the engine operating in it's optimum power band (RPM range) as much as possible. In this regard, the CVT is superior to the automatic and manual transmission. It's like having an infinite number of closely spaced gears. It also eliminates energy losses caused by shifting.
Are they necessary to have them in cars today?
There are still modern cars without CVTs.
Are CVTs any good regardless of the manufacturer?
Some are better than others. Scotty talks about how bad Jatco made ones are all the time in his videos
Is it better to have virtual gears rather than actual gears?
The virtual gears idea was only implemented to appease stubborn, non-mechanical people who get startled by change. I think it's stupid.
Are they even getting better fuel economy as compared to a regular automatic transmission?
Fuel economy yes. Longevity, no. So if you plan to own the vehicle a long time, any money you save on fuel will be completely defeated by the cost of replacing the transmission or the vehicle.
Better gas mileage is the main purpose. Generally, they are weaker than conventional automatic transmissions and need more maintenance as well.
Many companies make really bad CVT transmissions. However the cvt in the Toyota prius has been very reliable. There is a reason cab drivers use them, they can go tons of miles for very cheap.
IMHO, I don’t consider the CVT in the Prius a CVT. When I think of the term CVT, I think of two “gears/cones” that adjust accordingly to change gears using a belt or chain.
A Prius uses a planetary gear set. No belts. No chains. Just good old fashion gears. I don’t quite understand how it works, I just know it is different.
The Prius “CVT” is relatively resilient. Probably because of the gears and not chains or belts.
@kaizen
In fact, it is not a transmission at all. It only has one "speed". (Like an outboard boat motor for example). That means the ICE is outside of it's optimal RPM much of the time, and not working efficiently.
Toyota calls it a Power Split Device, and it is only for hybrid vehicles. It simply meshes together power from the ICE and the electric motor.
Hmm. So it’s basically one “gear”.
That is a fascinating choice to have an engine outside the ideal RPM range. I gather there must be a reason that Toyota does this.
It makes sense because the Prius never “shifts”.
The reason is that the electric motor is doing most of the work, and the ICE is just there to assist. The loss of efficiency in the ICE is more than offset by the gain from the electric motor.
@kaizen @mountainmanjoe Yeah the newer toyota cvt since the 3rd gen prius in 2010 are called a transaxle I think. The ones in the 2nd gen were more of a normal cvt with a belt. Those were pretty good though even in the 2nd gen, I would still rather have a regular transmission than one of the belt types though.
2nd Gen is the planetary gear set as well. Not sure about the 1st Gen.
I know Toyota also makes a traditional CVT. But I don’t think it is in the Prius or Hybrids. I don’t know for sure, just what I have gathered over the years.
They are what they are. They're extremely complex devices that I have a hard time getting my head around, and I've completed 4 of a 5 year mech engineering degree so far. The concept behind them is good, the transmission can continuously adjust to keep the engine at the most efficient RPM. They're small, and generally much more lightweight than a conventional automatic, since they have no metal gears, so they save fuel that way as well. There's no rev higher, then low and back up in the next gear... which wastes fuel.
I personally do not like them because of how they feel when they drive. My girlfriend got a 2019 Honda Civic as a rental car a while back with a CVT. I felt like the transmission was slipping because the engine sound doesn't change and it wasn't exactly an attention getter for acceleration that I could tell. Personally, I like the revving sounds you hear with standards and conventional automatics, as well the as torque and acceleration feelings when you upshift/ downshift.
Some CVTs emulate conventional multi-speed automatics with shift points. They avoid the rubber-band feeling but still have the problem of an unpredictable and relatively short lifetime.
Her rental had a sport mode, but all that seemed to do was let the RPMs go a little higher. The preset shift points in the emulator setting just sounds like an expensive fix when it breaks, forgetting it's aCVT. I'm curious how that works, now! Haha
Yes, we can blame the government's EPA mileage requirements for the CVT. I view the CVT as a desperate attempt to meet the current and future CAFE requirements.
From a mechanical standpoint, absolutely not. Due to their complexity, they have created the throw away transmission and throw away vehicle. When they break, I don't think they are being rebuilt. You will be looking at new or remanufactured replacement. Due to the expense, I'm guessing most CVT powered vehicles regardless of how good of shape the body is still in, are going to the junkyard instead of being repaired.
I think Honda and Toyota are neck and neck for the best CVT.
Actual gears only.
In theory a CVT transmission should be substantially more fuel efficient. Real world driving doesn't really reflect that from what I'm seeing.
In my opinion CVTs are structurally deficient and ineffective from an economic perspective. Despite what the manufacturers claim, they are useless for towing.
I felt like the transmission was slipping because the engine sound doesn't change
You’re describing the typical rubber band effect of CVTs.
Yeah, I couldn't think of a better way to describe it. Scotty's mentioned Toyota introduced the CVT with a launch gear instead of a belt. I'd be curious how that would change my opinion on them. The gear changing gives driving a car some life, I probably wouldn't like an electric car for the same reasons either.
I agree, the CVT feels very artificial to drive. Although I’ll admit that among all the CVTs out there, the one from Honda is probably the smoothest among them all. @dan doesn’t like the Toyota CVT design.
I have driven a 2015 Honda CRV going on 99K+ miles for the last 6 years.
It’s not as bad as folks make it out to be. If you are a regular consumer, I don’t think you can tell the difference between a CVT and an automatic. It just works.
Most consumers don’t probably care about CVT’s unless it breaks down on them. And that’s probably one of the big reasons for the shift towards CVT’s.
I can tell for sure. But that’s because I can tell the difference and know what to look for. TBH, I don’t mind it much. It’s a comfortable smooth ride.
With that said, this Honda CVT has performed flawlessly, just following basic maintenance.
My only concern is the potential longevity of the CVT. Only time will tell. So far so good.
I think you hit the nail on the head. It's just a matter of habituation. Once you get over the unfamiliarity, I can believe that CVT is a very comfortable ride, without the lurching that comes with conventional transmissions. Just smooth consistent acceleration, and engine purring away in its happy place.
We don't realise it, but our bodies anticipate the changing of speeds, and we pre-emptively tense certain neck and back muscles to compensate the sudden loss, and then gradual increase in momentum. So it's probably more relaxing on the body too.
Some years ago I test drove a Nissan Leaf, and I remember enjoying the smooth ride very much. It felt like gliding. It accelerated so smoothly that I often caught myself going quite fast and not realizing it.
The Hybrid car I've been driving in quite a lot recently (Kia Niro) has the Guinness World Records for lowest fuel consumption and it ain't a CVT.
CVT transmissions have no real purpose on Gasoline cars, and neither do they have a purpose on Hybrids - Hyundai-Kia and others' hybrids use dual clutch transmissions instead and although they're a bit slow and jerky it's really good enough to drive.
The reason why CVTs were used is to eliminate the inefficiencies that comes with conventional automatics at the time - looking at specs, Subaru's ±2012 LineTronic was 'more efficient' than a manual. Pretty much the same reasons why dual clutch transmissions became a thing, according to more data - their ±2012 PowerShift is only slightly less efficient than a Manual (3mpg difference).
For the time that was huge, as automatics were seen as money and fuel wasters - so having something that drives like an auto but is very good on gas was a huge deal. But, all of those transmissions are either extraordinarily jerky or bad to drive - or have serious reliability and maintenance issues.
"Getting it right" (making a DCT or a CVT feel food enough to use) requires you to make a lot of compromises (like conventional planatary launch gears on CVTs OR wet clutches with dual mass fly wheels and complex mechatronics on DCTs) that end up deleting any efficiency gains and add to inane mechanical complexity and even crazier maintenance requirements.
nowadays, modern conventional automatics - with torque convertor lockup, 6-10 gears, overdrive as standard and "economy gears" (the highest gear used typically only to cruise at speeds above 70mph, pretty much an extreme version of the overdrive gear) - there is no good reason not to use a conventional automatic as their efficiency has improved drastically. something like the TG-81SC allows the Peugeot 1.5L BlueHDi get almost 62 mpg highway with an Aisin EAT8 (a conventional automatic)
IMO the best gearboxes were some rare AMTs (automated manual, aka "single clutch semi-Auto" or "Clutchless manual"), most of them are total **** but some citroens (the OG inventors, they had automated manuals since the CitroMatic like 70 years ago) I drove were surprisingly good given the only thing that goes wrong on when is the clutch getting worn-out - but the clutch is just the same as in a regular manual so that's not even a big deal.
CVTs aren't good regardless of the manufacturer, they're for the most part bad regardless of the manufacturer. the only CVT I'm willing to bet on is the Toyota-Aisin K120 "Direct shift". It's insanely mechanically complex but it seems to be the way forward for Toyota as virtually all of their new cars (from the Euro Yaris 1.5L to the RAV4 and even the Lexus ES) are equipped with it.
Pretty much - IMO, CVTs are a useless piece of technology. Conventional automatics are on similar levels of efficiency and require much less costly maintenance while also lasting longer.
A Transmission that I can't wait to see is the tiny little CVT Toyota said they'll use for their Smart car sized crossover.
