This study presents a fully integrated, vehicle-level thermal management model for gasoline fuel tanks, designed to predict transient fuel temperatures, tank wall heating, and vapor generation under real-world driving conditions. The model simulates coupled thermal contributions from exhaust radiation, transient underbody airflow, conductive heat transfer, in-tank pump heating, and dynamic changes in fuel composition and level. Validation against on-road measurements shows strong agreement for fuel temperature and vapor flow profiles. Results confirm that exhaust radiative heating is the dominant thermal load, particularly during the post-shutdown heat soak period. A well-designed heat shield reduced peak tank wall temperature by approximately 27 °C, significantly lowering fuel heating and evaporation. Parametric analysis indicates that while fuel Reid Vapor Pressure (RVP) and tank material influence evaporation, their effect is secondary to external heat mitigation. While this model employs simplifications, such as assuming a uniform bulk fuel temperature and using empirically based convective correlations, these assumptions proved adequate for vehicle-level thermal management analysis. This adequacy is supported by the strong correlation between the model’s predictions and experimental field data across realistic driving scenarios. As a practical tool, the model successfully supports the optimization of thermal protection strategies and guides heat shield design decisions. Future work to incorporate measurement uncertainties, localized thermal stratification, and experimental validation of vapor composition would further strengthen predictive accuracy and extend the model's applicability to more detailed design phases.