A coupled thermal and computational fluid dynamics (CFD) full-vehicle model of a protected combat ground vehicle was developed and validated against measured test data. The measurement dataset was collected under thermally extreme conditions. Air temperatures were sampled inside the crew compartment of the vehicle under tactical idle operating conditions with space heaters substituted for on-board electronics. The results generated from the coupled thermal model correlated with the measured test data with an average absolute error of less than 2 °F for both simulated-electronics on and off conditions. The model was used to analyze thermal sensitivity to armor, insulation, and other factors affecting the efficiency of the HVAC system.