Abstract: A power system for a vehicle includes a motor, a flywheel and a transmission. Intermediate the motor and flywheel and coupled thereto is a first expansion pulley system with a second expansion pulley system intermediate the flywheel and transmission and coupled thereto. A programmable computer receives information concerning a desired vehicle speed and road level and processes the information so as to vary the motor r.p.m.s in order to reach a desired vehicle speed. The pulley systems effectively transmit the power from the motor through the flywheel and to the transmission at preselected ratios so as to provide for an efficient power delivery and vehicle acceleration. An additional expansion pulley system drives accessories at a constant preselected r.p.m. to preclude the transfer of needless power from the motor to the accessories.