Due to their harsh operating environments, military vehicle drive trains have special requirements. These special requirements are usually represented by hill climbing ability, obstacle negotiation, battlefield cross country travel, hard acceleration, high speed, etc. These special requirements need the vehicle drive train to have a wider torque and speed range characteristics than commercial vehicles. We have proved that larger constant power ratio in electric motor can significantly enhance the vehicle acceleration performance. In other words, for the same acceleration performance, large constant power ratio can minimize the power rating of the traction motor drive, thus minimizing the power rating of the power source (batteries for instance). Actually, extension of the constant power range can also significantly enhance the gradeability, which is crucial for military vehicles. Our design calculations show that the vehicle gradeability can be doubled by increasing the constant power ratio from 1:3 to 1:5. Based on a military vehicle performance analysis, various candidates among the electric motor drives have been evaluated, including the induction motor, the Brushless DC motor, and the Switched Reluctant motor. The purpose of the paper is to find the appropriate traction motor for the military vehicle.