The speed regulating system (10) for use in a road vehicle has inputs from the throttle pedal sensor (22), a vehicle speed sensor (24), the idle position of the pedal (26), engine speed (28) and engine load (30). Internally a memory stores the reference speed (Vsoll) and this is compared with the actual speed with the difference received by the regulator (44) that issues an overall reference (SOLLR). Threshold switching stages respond (70,74) when a set level is reached and this cuts off fuel to the engine.
