This paper describes a computer program termed IMPACT which was developed by the Research Department of VOLKSWAGENWERK AG. This program represents an aid in simulating vehicle crashes. The special feature of this program is that the actual crash models for front and side impacts are imbedded in an optimization algorithm. Various target dimensions, including numerous secondary conditions can be defined for optimization. In general, no single crashes or types of collision are taken into consideration for the optimization, rather a simulated accident world is set up, which is composed of vehicles of different masses, of several types of collision and various speeds. This contribution deals essentially with the crash model used.