SIMON is a new 3-dimensional vehicle dynamic simulation model. The capabilities of the model include non-linear handling maneuvers and collision simulation for one or more vehicles. As a new model, SIMON must be validated by comparison against actual handling and collision experiments. This paper provided that comparison. Included in the validation were lane-change maneuvers, alternate ramp traversals, limit maneuvers with combined braking and steering, vehicle-to-vehicle crash tests and articulated vehicle handling tests. Comparison against other models were included. No metric was provided for handling test comparisons. However, statistical analysis of the collision test results revealed the average path range error was 6.2 to 14.8 percent. The average heading error was -4.7 to 0.7 percent. Delta-V error was -1.6 to 7.5 percent.VEHICLE SIMULATION has many uses in the vehicle design and safety industries. Applications include suspension modeling, vehicle-tire system modeling, brake system modeling, virtual prototyping and compliance testing (ISO braking and lane change maneuvers) and safety analysis (collision simulation and post-crash reconstruction of actual on-road events).Advances in vehicle modeling and computer hardware and software technologies have made possible significant improvements in vehicle simulation, resulting in newer and more powerful modeling capability. For example, simulations in the 1980's and early 1990's typically used 2-dimensional models employing three degrees of freedom. More sophisticated models existed, but were seldom used because of their crude user interfaces.In 1996, the HVE simulation environment was introduced [1, 2, 3, 4, 5 and 6]*. HVE (Human-Vehicle-Environment) was developed as a sophisticated, 3-dimensional user environment for setting up and executing simulations involving humans and vehicles interacting with their environment. HVE was designed to be a general purpose tool, making few assumptions about the details of the actual simulation. Those details were left up to the designer/programmer of the simulation model.In 2001, a new HVE-compatible simulation model, called SIMON (SImulation MOdel Nonlinear), was introduced. SIMON provided the capability to simulate maneuvers involving 3-dimensional vehicle dynamics, such as driving on irregular terrain and vehicle rollover. With the addition of DyMESH , SIMON provided the capability to simulate collisions involving over-ride and other 3-dimensional collision issues. A report was published , providing the technical details and capabilities of the SIMON model. This is the second technical report on SIMON. This report presents the results of a detailed validation study of the SIMON model.