Vehicle thermal protection is an important aspect of the overall vehicle development process. It involves optimizing the exhaust system routing and designing heat shields to protect various components that are in near proximity to the exhaust system. Reduced time to market necessitates an efficient process for thermal protection development. A robust procedure that utilizes state of the art CFD simulation techniques proactively during the design phase is described. Simulation allows for early detection of thermal issues and development of countermeasures several months before prototype vehicles are built. Physical testing is only used to verify the thermal protection package rather than to develop heat shields. The new procedure reduces the number of physical tests and results in a robust, efficient methodology. In the past, complexity of the geometry involved in vehicle under-hood and underbody environments rendered traditional mesh generation approaches impractical and time consuming. The current work uses an interior-to-boundary method wherein the need for creating a ‘water-tight’ surface mesh is not a pre-requisite for volume mesh generation. This significantly reduces grid generation time allowing for the integration of CFD simulation into the thermal protection development process. The application of the new method is demonstrated for an actual passenger vehicle underbody model. Coupled radiation, convection, conduction simulations are performed to obtain the complete airflow and thermal map of the underbody. Results are validated with test data.