A drive train energy system is provided for a motor vehicle of the type having a drive shaft which rotates a drive shaft pinion that is transversely engaged with a differential crown wheel which operates a rear axle and a pair of wheels. The drive train energy system consists of a second crown wheel mounted to the drive shaft proximate the drive shaft pinion, with a second pinion transversely engaged with the second crown wheel. A driven shaft is connected to the second pinion, while a flywheel is connected to the driven shaft to be rotated thereby. A plurality of flyballs are spaced apart and pivotally connected to the flywheel so that when the flywheel is rotated and reaches a predetermined speed, the flyballs will pivot outwardly from the flywheel to increase the momentum of the flywheel to help maintain the speed of the rear wheels of the motor vehicle at higher speeds.
