Increasing power requirements along with weight and space constrains requires implementation of more intelligent thermal management systems. The design and development of such systems can only be possible with a thorough understanding of component and system level thermal loads. The present work implements 1-D and 3-D unsteady CFD based simulation tools in vehicle design process. Both under-the-hood cooling and HVAC systems are simulated in various operating conditions on a HPC Computer Cluster. System variables are optimized with gradient based BCSLIB and SciPy optimization libraries. The simulation results are compared and validated with experimental tests.