The sound quality of the car audio system is affected by the serveral factors such as the dimensions of the room, the boundary condition of the wall, the location of the speakers, etc. Among these factors, the location of the car speakers has been focused to find the best location of the car speakers assuming that the flat response is better. To verify the suggestion, the subjective test is adopted using 10 people. The developed method is utilizd to evaluate the function of the audio system with fixed speaker position.