How do you validate a full-vehicle dynamics simulation model?

Model validation involves correlating simulation outputs with physical test data at multiple levels: Component level (tire model with tire test data, spring/damper characteristics), subsystem level (K&C rig measurements vs kinematics model), and vehicle level (straight-line, steady-state, and transient maneuvers). Key metrics include understeer gradient, yaw rate response, body roll, and tire slip angles. Validation criteria typically require <10% error on primary metrics. Process includes sensitivity analysis, parameter identification using optimization algorithms, and documentation of model fidelity limits for different use cases.