Continuously Variable Transmission is an automatic transmission that uses two pulleys with a steel belt running between them. A continuously variable transmission makes accelerating smooth and offers enhanced fuel economy.
source/image(PrtSc): Thomas Schwenke
The CVT simultaneously adjusts the diameter of the drive pulley that transmits torque from the engine and the driven pulley that transfers torque to the wheels.This animation explains the basic principle of CVTs (continuously variable transmission). Here, we look at the Variomatic and the Multitronic. Watch the video from Thomas Schwenke for more info:
The flexibility of a CVT with suitable control may allow the input shaft to maintain a constant angular velocity even as the output speed varies.
When power is more important than economy, the ratio of the CVT can be changed to allow the engine to turn at the RPM at which it produces greatest power. This is typically higher than the RPM that achieves peak efficiency./wikipedia