Method and apparatus for vehicle cruise control

The speed regulating circuit (1) on board a road vehicle uses a radar transmitter and receiver system (3) and also receives signals (6) from an accelerator pedal (5). The radar signals (4) and the accelerator pedal signals are fed to an input switching circuit (2). A data bus circuit (8) transmits the input data to a computer (7) and an output circuit (11) which generates signals (13,15) to control the engine throttle valve (12) and the brakes (14). The computer has a two-way connection (10) to a data storage circuit (9).