Why your next vehicle may have a different transmission(Read article summary)
Continuously variable automatic transmissions, also known as CVTs, are gaining momentum in today's car industry. Why is this happening, and what will happen to conventional automatic transmissions?
Like it or not: Nearly every new vehicle—we're talking around 95 percent—has an automatic transmission of some sort. And manual transmissions are rare today, except among a few performance-oriented models.
That's the obvious. What might not be so apparent to new-car shoppers is that the portion of vehicles with automatic transmissions—or at least automatics as we know them—is falling, too. And because of what's replacing them, you, as a smart shopper, should understand the differences so that you get the right kind of running gear to meet your expectations.
So-called conventional hydraulic automatic transmissions, typically today with five to nine dedicated speeds (gears), aren't going away anytime soon; but two other alternate designs, dual-clutch gearboxes and continuously variable automatic transmissions (CVTs), both claim improvements in both performance and fuel efficiency. And one of them—the CVT—is gaining traction in the market at a far faster rate.
Both of these newer types boast some pretty pronounced advantages in mechanical simplicity over those conventional automatics, with their multitude of gears, solenoids, and hydraulic valving (they’re often the single most expensive component in a vehicle, before the engine in many instances).
Both simple in design, but potentially flawed in delivery
The idea behind CVTs is easy to understand: a heavy-duty drive belt (or chain) runs within a grooved pulley system with hydraulic actuators allowing the affective ratio to be infinitely varied within a range of ratios, seamlessly.
As for dual-clutch gearboxes, there are two separate automated manual gearboxes, each with its own clutch, but one containing the odd gears and the other the even ones. So, for instance, as you're accelerating, each respective gearbox readies the next gear up.
Both of these transmissions are quite simple in theory and elegant in layout, but there are some hurdles in the execution; and getting them right—and getting them to effectively be what we expect an automatic transmission to be—depends tremendously on calibration, software, and tuning.
And their flaws are completely different, which makes them each well-suited for some kinds of cars and ill-suited to others:
Dual-clutch automatics tend to offer snappy, coordinated shifts when you're driving quickly—and a little more driving enjoyment than a typical automatic—but at low speeds they're often not very well coordinated.
Continuously variable automatic transmissions (CVTs)—often considered the uninspiring alternatives—keep the engine in its sweet spot for acceleration (or fuel-efficiency) but often to the detriment of noise and vibration, leading to complaints of a disconnected, 'motorboating' feeling when accelerating—in which the note of the engine isn't connected to a sensation of speed. At their worst, CVT transmissions can feel sluggish, or as if something is uncertain or slipping.
CVTs at 10 percent and growing
Among new vehicles with automatic transmissions, more than ten percent now have CVTs, and that percentage is growing each model year. That's because it's not just niche models; top-selling models like the Toyota Corolla, Honda Accord and Honda Civic now have CVTs on their most popular models, as do family mainstays like the Subaru Outback and Forester.
“CVTs have proven that they work much better on mainstream vehicles,” said Jake Fisher, director of auto testing for Consumer Reports.
CVTs typically offer fuel-efficiency gains that are as big as those brought by eight- and nine-speed automatics, yet they cost less. That's part of the reason why Nissan—and CEO Carlos Ghosn—pursued them as a long-term commitment back when they were an unpopular option that few other automakers embraced in a big way.
It hasn’t exactly been a smooth road, either. Chrysler and Ford both tried CVTs in many of their vehicles, then backed away, with consumer acceptance part of it.
That commitment has proven a mixed bag over time for Nissan. The automaker has had some quality concerns and issues with perception for its CVTs, and most recently, Consumer Reports has seen some issues with the JATCO transmission in the Altima. “We currently don't recommend the Altima,” said Fisher, “And reliability—and the CVT—is part of it.”
Fisher thinks that CVTs are at a natural disadvantage against the latest and best automatic transmissions, and that it's mostly a perception issue, not an issue of performance.
CVTs rationally better, but lacking the driver connection
“With anything that follows fixed ratios, you have the direct connection,” he explained, and that makes the driver feel more satisfied and in control. “Across the board we’ve seen this—that the CVT improves fuel-efficiency, decreases satisfaction,” said Fisher.
And a number of automakers are finding ways to calibrate their CVTs in ways that restore that feeling of connectedness for the driver. For instance, recent CVTs in Honda, Subaru, and Toyota models will all 'catch' particular ratios during acceleration and follow them up the rev range—probably paying a very slightly penalty in efficiency or performance—in order to maintain more of a 'natural,' seat-of-the-pants feeling of acceleration.
Dissatisfaction with CVTs has, now and in the past, been less related to performance as it is to noise, Fisher says, and that's why some of the latest CVTs make slight sacrifices in performance in order to provide a more satisfying sound. The transmission in the Honda Accord is especially fairly impressive for that, he notes. “And really it’s a small price to pay for better noise characteristics.”
But there's no substitute for a set, predictable ratio that you can lock in, when you're on a mountain road, a steady downhill grade, or even a racetrack situation. “Clearly the manufacturers hear this, and that’s why they’re putting in fake ratios which, ironically, hurt performance,” said Fisher.
In the 2015 Subaru WRX, for instance you can tap into eight simulated ratios in a dedicated mode, while the Nissan Juke has a similar feature; and even the 2014 Toyota Corolla S offers seven 'speeds.'
There are plenty of indications that all the effort is working with consumers—to the extent that some owners might not even know they have one.
“In our latest Vehicle APEAL Study (2013 MY), owners with CVTs reported virtually the same satisfaction levels as owners with manuals or traditional automatics,” commented David Sargent, J.D. Power's vice president, global automotive. The APEAL study examines what consumers like about their new vehicle after 90 days of ownership.
Maintenance: where traditional automatics still have the advantage
Although CVTs might offer a cost advantage to the automaker, and help keep sticker prices down, they're not necessarily lower in upkeep to the owner. At a time when many conventional automatic transmissions are sealed and essentially maintenance-free for 100,000, or more in some cases, many CVTs might require rather costly fluid changes—which can also quickly erase any money saved on a slightly fuel-economy advantage.
But much of the data shows that CVTs are leaving owners satisfied. In J.D. Power’s latest Vehicle Dependability Study (VDS), which goes back three model years (2011, in this case), CVT vehicles had the lowest rate of engine/transmission problems.
As for dual-clutch gearboxes, they're hardly maintenance-free either. For instance, VW's DSG still surprises owners with its requirement for fluid and filter changes at 30,000-mile intervals—for several hundred dollars a pop.
The one-track mind of dual-clutch gearboxes
“There are clearly a lot of issues with dual-clutch gearboxes,” said Fisher. “We don’t see a lot of them in high-volume models, and there's a reason for that.”
“We see a lot of vehicles with jerkiness,” especially at low speed, explained FIsher. “And as the clutch wears, you end up with these situations where there’s a non-linear power delivery.”
Fisher pointed out that you need only take a cursory look at federal (NHTSA) complaint data for certain models to get an idea of how commonly dual-clutch gearboxes are malfunctioning, or at the very least misunderstood.
Like CVTs, dual-clutch transmissions offer the potential for greater performance (by the stopwatch) and better fuel economy, compared to regular automatic transmissions, yet they sacrifice some drivability and general smoothness to get that.
Many of the dual-clutch gearboxes seem to be tuned for top performance, Fisher observes. “With all these, zero to 60, or quarter-mile, they’re flawless. It’s in the mall parking lot where they can be a disaster...in those extended drives, in transitions, where they’re on and off the gas.”
Ford has gradually improved the software controlling its PowerShift dual-clutch gearbox that's used in the Focus and Fiesta—to the extent that it's expected to renew its vows with them in next-generation versions. Chrysler, meanwhile, has been withdrawing from plans to put its DDCT dual-clutch gearbox in more U.S. vehicles; after a lukewarm reception, it's only now offered in one trim level of the 2014 Dodge Dart (the Aero), and in the Fiat 500L.
“They’re having a hard time getting these smooth” for U.S. driving conditions, said Fisher. “It’s very confused in the 500L.”
CR recommends staying away from it, as well as from the Ford unit. “Although Ford has really worked hard to get it better,” Fisher said.
Myths versus reality
There’s no reason to believe that a CVT will be any less reliable than a conventional automatic, or have fewer trouble-free miles overall. That's confirmed through Consumer Reports reliability data, which is based on on detailed responses from subscriber experiences with 1.1 million vehicles.
Longevity is another myth; with the exception of some early V-6/CVT combinations, which we shall refrain from mentioning here, there are no indications that CVTs have a shorter life cycle.
Of course, there are some indications that say otherwise. In J.D. Power's VDS—again going back three model years—those owning vehicles with dual-clutch gearboxes report the highest satisfaction.
But it's also hard to say that either CVTs or dual-clutch gearboxes are pushing the versatile, refined traditional automatic transmissions out of the market—especially at the premium end of the market. Fisher points to the ZF eight-speed automatic transmission that's used in a number of luxury and performance-oriented cars as an example of just how good conventional automatics can get. Versus that, and some other newer multi-speed automatics, Fisher, argues, “I don’t think you’d point to the CVT and say that it’s superior, in terms of how it drives.”
Are you sure you won't go manual?
The percentage of new vehicles sold with a manual transmission has fallen to around five percent—lower by some calculations. That change is easy to see, for anyone who remembers the greater number of manuals on lots just, say, 10 or 15 years ago.
Although CVTs, and even some dual-clutch gearboxes, get better EPA mileage ratings than manuals, a manual gearbox, driven properly, is still the transmission choice with the lowest cost over the long run, Fisher says.
And while shifting it yourself is still in vogue for a certain kind of performance car, manual-shift versions of mainstream models—from cost-conscious sedans to rugged crossovers—continue to disappear from the market at what is (to us) an alarming rate. Meanwhile, there’s no doubt that smartly tuned CVTs will be appearing in more new models.
So do you want a car with gears? Do you want to shift? Or would you rather not even care to notice most of the time? Just be aware that you have plenty of choice in that.