Automatic engine shut-down / start-up system for motor vehicles, and method for its operation

The invention relates to an automatic engine shut-down / start-up system for motor vehicles and process for its operation in which a device for measuring the distance and / or the differential speed of relevant objects in the direction of travel, in particular preceding vehicles is provided and the control device in dependence on the presence of predetermined conditions of the distance and / or the differential speed on the automatic engine shutdown and / or the automatic restart of the engine is decisive. Thus, a motor cut-out preferably takes place only when the vehicle is stationary and at a COSTANT over a period distance from the preceding vehicle, and a starting of the engine, if the distance or the speed difference increases toward the preceding vehicle.