The US Army Tank-automotive and Armaments Command (TACOM) has the mission of procuring and managing the Department of Defense (DOD) ground vehicle fleet of both wheeled and tracked vehicles. TACOM's Research, Development and Engineering Center (TARDEC) provides engineering and scientific support to vehicle designers, developers and system managers, an important aspect of this support is directed at maximizing the capability and performance of Department of Defense (DoD) ground vehicle systems and ensuring the safety of their personnel. In order to reduce the time required to deploy troops and equipment, engineers on TARDEC's Analytical Simulation Team have been investigating vehicle modifications which will lead to an increase in the mobility and stability of the DoD vehicle fleet. In this paper I will describe the Modeling and Simulation effort undertaken to identify strengths and weaknesses in the dynamic performance (handling, stability and ride quality) and braking performance of a wheeled military troop/cargo transport vehicle. I will describe modifications made to the model in an effort to improve vehicle performance as well as the impact these modifications made on the overall vehicle performance.A high resolution, 3 dimensional multi-body model of our test case vehicle system, a 6x6 solid axle truck with a payload capacity of 4540 Kg. was developed, and was exercised through a series of “virtual performance tests” on the computer in order to evaluate vehicle stability during on- and off-road use. This paper will include field and simulation data which was used to “validate” this test case baseline vehicle, as well as the results from simulations which were used to quantify the vehicle's performance per vehicle configuration. I discuss findings made regarding tire configuration (dual 11.00R20 and single 14.00 R 20), payload placement, and performance improvements made during towing of heavy loads.The paper is intended to invite comments and criticisms from the Engineering and Scientific community engaged in vehicle performance evaluation and optimization using simulation and/or field testing.