This paper deals with an innovative optimization procedure for multi-physics analysis of electrical machines using Motor-CAD and optiSLang software. The approach is based on cutting edge sensitivity analysis, meta-modeling and optimization techniques that enable motor designers to leverage the design space and to find an optimum solution with respect to a given specification. A detailed optimization workflow is developed and applied to the design of an interior PM motor for a PHEV application. In particular, the electric motor is optimized to give maximum efficiency, minimum size and minimum cost, while achieving specific peak and continuous torque-speed characteristics.