Noise waveform analyzer was developed to measure the statistical distributions such as amplitude probability distributions of noise envelope. Using this system installed in a van, some statistical distributions of automotive radio noise in lower frequency microwave bands (1-3 GHz), received while driving on main streets and expressways in Tokyo, were measured to provide fundamental data for designing mobile communication systems in this frequency band. Variation of the impulse height, received in typical driving conditions, can be expressed by a log-normal distribution and impulse emission seems to be Poisson-distributed in time for time history records as long as 40 minutes.