This paper describes the contribution of simulation to the development of the new Automotive Stability Management System (ASMS) of ITT. The benefits and limitations of simulation especially with respect to experimental testing with prototype vehicles are discussed. The paper will outline how cost and time to market have been reduced by Off-Line Simulation (OLS) and Real-Time Simulation (RTS). During the development of ASMS, new control algorithms were designed and first validated in the laboratory. Simulation has offered an insight into the vehicle dynamics that is difficult to obtain with prototype vehicles. It has been possible to study the interactions of the vehicle control system and vehicle dynamics under all circumstances. Some simulation examples of typical maneuvers are discussed.