Continuously variable transmission

The Continuously Variable Transmission (CVT) does away with fixed gears in favor of a pulley system, which can constantly adjust the drive ratio to best match the optimum engine speed. And instead of the limited ratios, tied to the number of gears, in a conventional automatic transmission, the CVT offers potentially thousands, depending on the system. Letting the engine run at an optimum speed for as much driving time as possible leads to greater fuel efficiency.

Past CVTs have not been able to handle high engine output, although the technology has improved considerably. And with some CVTs, drivers will find a disconnect between engine sound and vehicle acceleration.

The CVT is a very old concept, and versions of it have been used in cars, light tractors, and motorcycles over the last century. Nissan is currently a big proponent of the technology, while Subaru and Audi have their own offerings.

Example: 2012 Nissan Altima