CVT?

"Dan Saba" haute in die Tasten:

CVT stands for Continuous Variable Transmission, this means that the transmission is able to change its transmission ratio almost stepless. So instead of having 4, 5 or 6 gears, you have hundreds;-)

Early CVTs worked with two cones on one axis. These cones could be moved an their axis and would form a transmission disc with variable diameter. A belt runs over that disc and transmits the power. These simple CVT are used to a large extent with Motorscooters, Snowmobiles and such. Their disadvantages are low mileage and the limited ability of bearing raw torque. The dutch car maker DAF began in the 50's to make tiny compact cars with such a CVT, try google for the keywords "Daf", "Variomatik" and maybe "Daffodil". Audi has improved the principle and exchanged the rubber belt against one out of special steel elements. The Audi gearbox can stand more torque and is said to cause no additional fuel consumption.

Frank

Yes, what Frank said, but I will add a few things. The Subaru Justy was also offered with a CVT, but used an older rubber/fiber belt design. The Audi implementation of the CVT is known as the Multitronic Transmission. Instead of using two cones, it actually uses four, two per axis on two parallel axis. The belt is actually a wide chain system made from a special high-strength metal allow. See the link below for a photo:

The Nissan Murano and the Saturn VUE also offer CVT's. I am not familiar with their designs, but I would assume they would be similar to Audi's given the amount of torque produced by their engines. Not only is the Audi Multitronic able to withstand more torque than the older belt designs, it is also more fuel efficient and provides faster acceleration than either their manual or conventional automatic transmissions.