Thermal management is of vital importance in the development of a scooter type motorcycle (two-wheeler). Traditionally the thermal management development of a two-wheeler is done through experimental methods, or using sub-system level CFD models. In current work, a comprehensive, complete vehicle, three-dimensional CFD model has been developed to assess thermal performance of the scooter and its sub-systems. The model can predict thermal performance in different operating conditions, such as, wide open throttle, idling and key-off. A typical thermal interaction in engine happens through metal contact conduction, air cooling and oil flow path in the engine. The model can capture the sub system interaction, such as, an interaction between the cooling system and engine cabin. Modeling oil is computationally expensive, as it involves complex physics modeling such as multiphase flow. An energy balance based new sub-model is added to the CFD model which can predict the engine oil temperature without modeling the oil flow inside the oil sump. A good correlation for this new sub-model has been achieved between CFD model and on-road experimental values. The air and solid temperatures at different locations of engine and vehicle from CFD model has been validated with the on-road measurement. The time to build and evaluate a design is being reduced to one fifth with this new method, and incorporating any design change in the model and its evaluation through CFD is reduced to one tenth. Finally, a case-study has been presented to demonstrate how the model has been used in product development process by capturing various failure modes early in the product development process and resolution of these failure modes using model and test.