Abstract: A system and method for determining absolute vehicle height and ground speed. As disclosed, a millimeter wave radar system for determining selected boundary distances is implemented based upon a generation of a modulated millimeter wave signal which is envelope detected and thereafter phase detected to determine the selected boundary distance on a continuous real-time basis. To similarly determine absolute vehicle speed on a continuous real-time basis, a method is disclosed for use in cooperation with an on-board microcomputer, the height sensing system described above, and a passive speed sensor aperture which is affixed to the chassis and directed toward the ground at some angle theta. In operation, a portion of the RF signal radiated by the height sensor is backscattered toward the passive speed sensor aperture. The Doppler Shift of this signal caused by vehicle motion is determined.