A diesel engine coupled to a CVT (Continuously-Variable Transmission) was computer controlled to maintain constant CVT output speed. The engine operated on power demand on a torque-speed schedule giving low BSFC. The engine-CVT-computer combination is viewed as an augmented engine, to which a conventional power train can be added to produce required vehicle speeds. On farm tractors, the pto (Power Take Off) shaft and other functions requiring constant speed would be driven by the CVT output shaft. Fuel savings with the augmented engine depend on engine load; at half load or less, a prototype augmented engine produced fuel savings of 15% or more.