A methodology for design and development of commercial vehicle cooling system is derived with an objective to minimize part cost, engineering resources and time to market. This approach is very useful in companies with more variant of engines and vehicles. For this it is identified to have a common cooling system for a set of engines. A systematic approach to develop cooling system based on heat rejection is conceptualised. Engines are classified based on heat loads in to various groups. The cooling package selected for a particular group is independent of type of vehicle (bus or truck), cab (day, sleeper, FES or FBS), Type of drive (LHD or RHD), Emission norm (BSIII or BSIV) and fuel (Diesel or CNG). These packages will cover up the entire range of vehicles and engines. The packaging space available for each group is derived and the cooling package size is finalised. Fan and fan pulley options are listed based on air flow and fuel efficiency requirements. Parameters evaluated are Limiting ambient temperature, Intake manifold temperature difference, CAC pressure difference and fan power consumption. Down flow radiator and cross flow CAC is selected meeting the cooling targets. The Thermal Systems Modeling and Simulation is done using 1D simulation software. Interchangeability between parts (Radiator, CAC and shroud) of different makes is ensured in terms of performance and in the field one make part can be fitted on another.