Method for operating a speed regulation system of a motor vehicle and motor vehicle

The method involves regulating a speed of a motor vehicle (1) to a driver sided selectable desired speed in a normal operating mode. A consequent operating mode is activated as reaction on a preset driver sided operating action by a running ahead reference vehicle on a same traffic lane. The reference vehicle is detected by an environment sensor (4) e.g. radar sensor. A temporal or spatial interval i.e. time gap, to the reference vehicle is regulated by the reference vehicle driving slower than the desired speed.