In recent years, many optimization methods have been raised to deal with the fuel and cost efficiency problems of the new generation cars. This study reviews two primary optimization methods, one for pure electric cars and one for hybrid vehicles, with detailed explanations. For electric vehicles, methods for designing electric powertrains that are energy efficient while sustaining vehicle dynamics and ride quality are discussed. The three characteristics of energy consumption, dynamic performance, and ride comfort are optimized using modeling, and the final optimization method is determined, which can achieve a 93.5% improvement in lightweight and a 92% improvement in power transmission. Four standard powertrain transmissions are mentioned for hybrid vehicles with advantages and limitations. The most promising multimode information is selected to work with a single EM instead of the dual EMs that conventional hybrid cars contain. The simulation results of the single-EM HEV with the MMT model and its comparison test with the "THS II-LIke'' vehicle, holding the same parameters except having dual EMs, show the well-performance of this method in energy loss. In the end, a more efficient engine, the Atkinson engine, for hybrid vehicles is illustrated to substitute the traditional otto cycle engine.