Electrical vehicles (EVs) have attracted the attention from the entire world for their potential use in future transportation system. As the crucial drive component for EVs, various types of electrical machines have been evaluated in terms of efficiency, power/torque density, speed range, fault tolerance, etc. This paper investigates the optimization method of the electrically excited synchronous machine (EESM) for EV applications. Prius 2010 IPM is chosen as the benchmark for comparison and the optimal design procedure is illustrated by considering the rotor saturation effect and drivetrain efficiency under city and highway drive cycle. Moreover, a PM-assisted EESM topology is introduced to enhance the torque density and the influence of different load conditions on the optimization is analysed. The results show that EESM has excellent performance in high speed region while its relatively low torque density and efficiency can be enhanced to some extent through optimization method.