Abstract: A system for storing deceleration energy from a motor vehicle and for using the stored deceleration energy to assist in accelerating the motor vehicle. In one embodiment, the system comprises a generator mechanically coupled to the drive train for converting deceleration energy to electrical energy, means electrically coupled to the generator for storing the electrical energy outputted by the generator, a motor mechanically coupled to the drive train and electrically coupled to the storing means for converting the stored electrical energy to mechanical energy used to assist in accelerating the motor vehicle, and a detector/switch for determining whether the motor vehicle is decelerating, accelerating, or neither and for switching the generator on and the motor off when the motor vehicle is decelerating for switching the generator off and the motor on when the motor vehicle is accelerating, and for switching the generator off and the motor off when the motor vehicle is neither accelerating nor decelerating.