Computer simulation and real-time, interactive approaches for analysis, interactive driving simulation, and hardware-in-the-loop testing are finding increasing application in the research and development of advanced automotive concepts, highway design, etc. Vehicle dynamics models serve a variety of purposes in simulation. A model must have sufficient complexity for a given application but should not be overly complicated. In interactive driving simulation, vehicle dynamics models must provide appropriate computation for sensory feedback such as visual, motion, auditory, and proprioceptive cuing. In stability and handling simulations, various modes must be properly represented, including lateral/directional and longitudinal degrees of freedom. Limit performance effects of tire saturation that lead to plow out, spin out, and skidding require adequate tire force response models. Additional steering and braking subsystem characterizations are necessary to represent important handling and stability requirements. Steering compliance and appropriate tire aligning torque effects provide a significant component of understeer. Front-to-rear brake proportioning plays a significant role in limit performance directional stability, including the effects of nonlinear brake pressure proportioning valves.This paper summarizes vehicle dynamics model requirements for various classes of interactive and computer simulations. General formulations include sets of force and moment equations, with subsidiary equations for effects such as tire force response, antilock, traction control, four-wheel steering, and other advanced vehicle control systems (AVCS). Examples of simple and complex models will be given, including validation methods, for vehicle and driver models.