Abstract: A vehicle transmission system is described which employs a split power path design to achieve continuously variable speed ratios. A motor-generator unit is provided for converting a fraction of the input power into electrical power, and a second motor-generator and differential gear mechanism are employed to re-combine the two power components before transmitting the mechanical power through a gearbox. Electrical power dissipation means allows the transmission system to provide slippage when accelerating a load from rest, and it also assists in shifting and in braking. An electronic motor controller coordinates feedback signals from various sensors and controls the dynamic performance of the entire system. The motor-generators are integrated with the housing of the transmission and have water jackets to assist in heat dissipation. The motor-generator pair and the power dissipation elements are all cooled by a circulating fluid which transfers heat from these components to an external heat exchanger.