The paper describes the compatibility of two contradictory factors among basic automobile design features through the development of an advanced research automobile. These factors are the interior space for passenger comfort and exterior shape for aerodynamic drag reduction. The basic design of the automobile is a fast-back front- drive car with packaging five passengers providing sufficient interior space resembling sedan. In consideration of safety regulations, the visibility and passenger comfort, body shape has been optimized by 1/5 scale model wind tunnel testing. Since engine cooling flow is one of the dominant factors among aerodynamic characteristics, resistance due to internal flow in the engine compartment are also explained. The drag coefficient of the advanced research automobile developed through aerodynamic studies was shown to be 0.25.