When considering charge-air cooling in vehicle engines, it is necessary to distinguish between commercial and passenger applications on the one hand, and Diesel and gasoline engines on the other. The requirements for the various types of application will be outlined, and the characteristics of the various charge-air cooling systems discussed.In general, heat transfer rate and pressure drop are considered in evaluating the suitability of a charge-air cooler for a particular purpose. The effectiveness of such a procedure, however, tends to be limited. In order to create new criteria for evaluation, new terms such as the efficiency of density recovery and “half-value performance” have been developed.Optimisation of the core geometry according to the requirements and desired objective functions is necessary and shows that one single system cannot meet the wide range of requirements. Some practical applications and future trends are outlined.