Abstract: A clutch control system for the automatic control of a motor vehicle clutch which connects an engine with a gearbox under the control of a driver-operated gear ratio selector lever. The control system includes an electronic control unit which controls initial clutch take-up on starting of the vehicle, clutch re-engagment following each ratio change, clutch disengagment on movement of the gear selector lever to change the operative ratio of the gearbox, and clutch disengagment on the coming to rest, etc. of the vehicle. The control system also incorporates an automatic calibration routine which is invoked on the inital keying-on of the system, said routine comprising a predetermined sequence of events in which the system responds to actions of the operator and at predetermined that the system is ready to proceed to the next stage of the calibration.