The problems relating to conventional vehicle engines and measures designed to reduce emission, specifically in the light of improving fuel economy, are discussed. Recent findings in the field of operational procedures for Otto and Diesel engines indicate numerous possibilities for reducing emissions and simultaneously improving the existing methods of operation. The development of new-type power systems for motor vehicles implies, however, many technological problems. Special attention is paid to the problems linked with the use of alternatives fuels for present-day motor vehicle engines. International exhaust emissions legislation, the development of new-type motor power systems as well as the development of components for conventional and new-type engines and criteria for new-type power systems are discussed.