A summary is given of the enabling technologies for real time high fidelity vehicle dynamics simulation. Methods of utilizing this technology to increase realism in an operator in the loop simulation are then discussed. Finally some of the research that can be performed using a high fidelity, highly realistic operator in the loop simulator is presented.Automotive engineers have long used sophisticated, batch job computer simulations of the dynamics of vehicles and vehicle subsystems to aid them in improving vehicle performance and safety. Recent technological advances have brought high-fidelity vehicle dynamics simulation into a new realm; that of real time. Integration of real-time high-fidelity dynamics into a ground vehicle simulator allows designers and experimenters to place human operators in the loop, enabling systematic investigation of critical questions concerning driver-vehicle interaction, human information processing, and measures of a person's fitness to drive and the impact thereon of various common impairments.Real time simulation provides a unique and powerful method for addressing these kinds of human factors questions - so important to vehicle safety and performance.