For discussing the differences in efficiency between a SI engine and a diesel engine in the vehicle a detailed split of loss calculation is used normally as method. The comparison of engine concepts at identical operating points gives only limited information. Using a modified method, now the concept-specific load collectives are taken also into account. In this article differences in efficiency between a SI engine and a diesel engine is introduced on basis of this method. Furthermore a split of loss calculation for the gas exchange is described, which allows to evaluate efficiency increasing measures for the gas exchange. The results are part of a research project (No. 875), which was put by the Research Association for Combustion Engines (FVV, Frankfurt/Main, Germany) and processed at the Research Institute of Automotive Engineering and Vehicle Engines Stuttgart (FKFS, Germany).