Regenerative braking

When kinetic energy normally wasted in the form of heat during braking is recuperated into the car’s battery in the form of electricity. This electricity can then be used to boost an electric car’s range. The physical effects of regenerative braking can slow the car down, at a rate that can now sometimes be adjusted by the driver, even when the brake pedal is not depressed.

http://youtu.be/y8jRAwIzPTM