Overreliance on petroleum products and environmental pollution from combustion emissions produced by automobiles has led to extensive research on hybrid electric vehicles, electric vehicles and their components. A key component in these vehicles is the electric motor, used for traction as well as powering other appliances like the compressor. Overheating in electrical motors results in detrimental effects such as degradation of the insulation materials, magnet demagnetization, increase in Joule losses and decreased motor efficiency and lifetime. Hence, it is important to find ways of optimizing performance and reliability of electric motors through effective cooling and consequently reduce operating and maintenance costs. This study describes 3D CFD simulations performed on a totally enclosed air over fan cooled brushless D.C. motor to identify the temperatures of the critical components of the motor. The energy sources are obtained from electromagnetic losses computed using MAXWELL, a commercial FEA software and bearing losses obtained through numerical methods developed by the authors. A finned casing is used as the heat sink and the effect of varying the fin geometry on the cooling performance is examined using three heat sink designs. The results show that the highest temperature occurs at the end windings and that this temperature can be reduced by up to 15% by introduction of a suitable finned housing. These results show that CFD can be effectively used to optimize the cooling performance of electric motors. Experimental tests are undergoing in order to validate the CFD results.