In-vehicle reverberation time as a function of frequency can be used as one indicator of the quality of a vehicle interior as an acoustic space. Typically, however, reverberation times in passenger vehicles are so short that they can be extremely difficult to measure using interrupted noise or impulse excitations. This paper investigates a steady state method of determining reverberation times by adapting the power injection method, which is typically used to determine composite damping loss factors of panels. The results of using this method will be compared with those of other methods. Theoretical and practical advantages and disadvantages will be discussed. Application of this method to absorption measurement will be discussed as well.