I answer a lot of questions on Quora. Many of those questions are about automotive things that may be of interest to CarNewsCafe readers. Like this one.
Why don’t all automatic transmission cars have gearless configurations like Subaru?
My Answer: There are limits to what a continuously variable transmission (CVT) can do. The design of a CVT has torque (power) output limitations that make it unsuitable for some applications, such as trucks, larger vehicles, and vehicles made for tasks involving large amounts of power output (off-roading, racing, etc). The Subaru Ascent, for example, is about as large as a vehicle can get and still utilize a CVT without incurring serious losses or mechanic problems in the transmission.
Some manufacturers have shied away from CVT use because of its inherent potential for breakdown. A CVT’s design is such that if the belt driving the transmission’s “gearing” were to fail, even only slightly, the entire transmission would also fail. The belts in CVTs have changed dramatically in terms of their composition over the past decade. For automakers, a decade is barely one vehicle generation. More and more are going to CVT use now that those belts have improved so much, but the transition for those who are gaining just as much efficiency by adding gearing to existing designs will be slow. If it happens at all.
Where CVT use really shines in terms of gained efficiency are in hybrid drivetrains, wherein two power sources (e.g. a combustion engine and an electric motor) are combined. Toyota uses this type of CVT design very effectively in their hybrid models. Yet the CVTs found in their non-hybrids are abysmal, largely due to Toyota’s engineers using outmoded thinking about gear shifts (which are mimicked) in the programming of those transmissions. Subaru and Nissan have no such delusions about what the public wants out of a CVT.
