Different techniques to reduce the aerodynamic drag of cars have been utilized in the past. Although the best results can be achieved with streamlined bodies, these have not generally been acceptable to the buying public. In order to make use of the potential of aerodynamics nevertheless, a procedure called detail optimization has been developed by Volkswagenwerk AG. Representative results achieved with this technique are reported. The step by step drag reduction of several passenger cars is illustrated. The consequent reduction in fuel consumption has been investigated for steady state driving as well as for standarized cycles.