This paper describes the architecture and use of a simulation graphical user interface (SGUI) that uses new (1990's) computer hardware and software concepts to provide an easy-to-use environment for simulating vehicle dynamics. The user interacts with windows, buttons, and pop-up menus, in a multitasking environment such as UNIX, Windows®, or Mac OS®. The SGUI reduces the level of computer expertise required of the user. Most information is shown in a graphic context, and “what if?” options are selected by clicking buttons and selecting from pop-up menus. The SGUI is organized as a data base of vehicles, vehicle parts, vehicle inputs, and simulation results. The organization makes it easy for users to assemble the component data needed to (1) simulate new systems, (2) run simulation programs automatically, and (3) view the results graphically.The SGUI is assembled from low-cost software components. Object-oriented graphical data-base programs, commonly used as the front end for on-line documentation and multimedia, are used to maintain the simulation data, manage input and output files, and run simulation programs and post-processing visualization tools.The architecture is extendible by users and developers. New data screens can be added without any programming on the part of the developer. Programming of the executable simulation programs is minimized by using a commercial code generator. Users can install new executable programs by making a simple menu selection.