High power density and high efficiency are prime requirements of motors intended for automotive applications. Therefore, interior permanent magnet synchronous motors (IPMSMs) are commonly used in hybrid electric vehicles and electric vehicles. It is known that the arrangement of magnets is a significant factor with respect to the performance of an IPMSM. In this paper, three motors with different magnet arrangements are investigated for use in automotive applications based on the 2-D finite element method, and the validity of the analysis is verified using a prototype machine. The results of the study clarify the influence of the magnet arrangement on the performance of IPMSMs as well as the characteristics of suitable magnet arrangements for automotive applications.