Current and future automotive systems are becoming more complex than ever. They consist of different subsystems such as the engine, transmission, cooling system, driveline, controls systems, HVAC and active/passive safety systems. Hardware and software development for each of these subsystems have different timeline’s. The subsystems are usually developed by different teams within an organization and in some cases are also developed by suppliers. These are some of the main hurdles for carrying out a system level analysis of the vehicle earlier in the development process. Model.CONNECT was used to overcome the above mentioned hurdles by connecting a driveline model, a cooling system model, thermal controller and two-phase flow models with minimal effort. Front loading of development activities due to limited availability of in-vehicle development time, the push for reduced costs and pre-prototype thermal analysis/design of an automotive system can be achieved with the help of such an integrated system level co-simulation. The integrated model was validated by comparing model results with experimental data obtained from EPA and SCO3 fuel economy driving cycle vehicle tests.