Most of the present LPG passenger cars and light trucks on the road are based on production gasoline engines. Various retrofit systems for LPG use are offered from different producers. The necessity for a large range of adaptibility to various engine types leaves limited space for individual optimization. Lack of equipment in some service stations is another reason for limited performance of many LPG vehicles on the road.Only the careful selection of a suitable LPG equipment and its best adaptation to the engine makes the full utilization of all advantages of this excellent engine fuel possible.Still better results can be obtained if the engine-vehicle concept is optimized to the LPG fuel as well. A lean burn engine promises low emissions at good performance, where the economy of the vehicle i. e. the operation costs depend on the local fuel prices in the different countries.