Abstract
Crank shaft end energy conversion efficiencies of a 1300cc engine are presumed by using the data of ECU and GPS at driving on a highway. They are full of 10-35%. However, each mean value of the round trip of the highway is about 30%. There are high values in some malfunctions that exceeded 35%, too, when they have been analyzed in detail. The cause is possibly judged that the engine is always connected with the wheel. For instance, the output powers do not necessarily become the lowest, though the foot parts from the accelerator pedal and the opening angle of the throttle becomes the lowest. As for the classification according to the driving condition, these efficiencies have corresponded to the driving condition.