The emergence of high-speed parallel computers, new mechanical system dynamic simulation formulations, and a range of driver-in-the-loop vehicle simulators is shown to provide a qualitatively new virtual prototyping tool to support military vehicle acquisition. The state-of-the-art of driver-in-the-loop simulation and projections regarding its refinement for use in military vehicle development are outlined, with emphasis on providing a virtual prototyping capability that accounts for operator-vehicle interaction, prior to fabrication and test of prototypes. It is shown that the potential now exists to investigate trade-offs involving vehicle design and operator effectiveness that heretofore required a physical prototype. This will permit the engineering community to optimize the design of military vehicles for the soldier, beginning early in the design and development process and continuing through product improvement. Bringing human factors into design consideration using virtual prototyping before engineering design decisions are finalized promises to be one of the most significant advances in Concurrent Engineering of military vehicles to occur in the decade.