Direct torque control (DTC) is one method to control ac motors, and has been taken into consideration in recent years due to the numerous benefits. In conventional method of DTC, stator flux vector trajectory always follows a circular path, while the stator flux and torque remain within a hysteresis band by selecting the appropriate voltage vectors. In several applications, due to the limited supply voltage, a six step motor control is required at high speed. However with a conventional DTC, due to its inherent characteristics of the switching and the unavailability of the reference voltage, the six-step mode required at high speeds is not possible. In this thesis at first a new method is proposed for the continuous control of the interior permanent-magnet synchronous motors (IPM) using the DTC and the effectiveness of this approach in improving the performance of the electric cars has been examined. In proposed scheme, the over-modulation control is achieved by changing the trajectory of the reference flux from circular to hexagonal path. In this way, the change of the output inverter voltage wave from the high switching frequency to the six step mode would be in a smooth and continuous transition. Using the six-step voltage, constant torque region expands and the capabilities of the torque increases in the flux weakening region. In the proposed method also the continuous transmission of control from six-step mode to the high-frequency switching is possible. The simulation results and comparison with the results of the hysteresis DTC drive, confirms the dynamic improvement and stable torque performance. The performance of the proposed drive is also examined in an electric vehicle application. Simulation results show the effects of the proposed method in improving the maximum cruising speed, gradeability, braking capability, acceleration and efficiency. Keywords: Direct Torque Control, IPM Motor, Overmodulation, Electric Vehicle