The thesis deals with the modelling and optimization of electric machines for Hybrid Electric Vehicle (HEV) purposes, considering the driving strategy. Through simultaneous optimization of electric machine and driving strategy, the maximal fuel saving potential of a parallel HEV can be achieved. Additionally, the Asynchronous Machine (ASM) and the Permanent-magnet Synchronous Machine (PSM) can be assessed in terms of vehicle fuel efficiency.By means of literature review, alternative electric machine types are investigated butexcluded for further research because they show no advantage in efficiency andpower density and require higher development costs than either ASM or PSM types.