Due to the effect of global warming and skyrocketing price of oil, it is important to address the issue relating to the utilization of fuel and fuel efficiency in road transportation. Purely electric vehicles are seen as a long-term solution to this problem, but existing batteries cannot store enough energy to give a satisfying distance range. However, hybrid powertrain are originally conceived as a way to compensate for the shortfall in battery technology. As a product of advanced design philosophy and component technology, the maturing and commercialization of hybrid technologies demand extensive research and development. In this book, a 1325kg series-parallel gasoline-electric vehicle (GEV) having a maximum internal combustion engine (ICE) and electric motor power output of 57KW and 50KW respectively was modeled and simulated using MATLAB/simulink. The energy and cost savings potential of the GEV was evaluated using simulated high way fuel economy test (HWFET) and urban dynamometer driving schedule (UDDS) drive cycle data.