During the past years advances in fuel efficiency of car engines did not result in the expected reduction in overall fuel consumption of new car generations. One reason is the increasing vehicle weight. In an overall–weight analysis of an automobile the engine and as part of it, the crankcase represents a single component with a high weight reduction potential. This paper discusses weight reduction strategies using lightweight materials and modern design approaches.The application of lightweight materials for new crankcase concepts implies comprehensive design considerations to achieve weight reductions as close as possible to the potential of the selected material. A specific approach for inline and V–engine crankcase concepts is discussed in detail. Engine weight reduction can also be achieved through substituting large and therefore heavy engines with small high performance engines. Modern technologies applied to existing engine concepts increase the power–weight ratio, the engine's capability and therefore its marketing value.New lightweight design strategies allow a significant reduction of engine mass compared to conventional concepts and represent an important contribution to reduce the overall vehicle weight.