Abstract: Disclosed is a vehicle speed limiter for use with a vehicle throttle system comprising a mechanically actuable throttle member, an engine speed controller, and a throttle signal unit in data communication with an engine speed controller and operably coupled to the throttle member so as to generate an electronic throttle signal in functional response to the degree of actuation of the throttle member, and to transmit a throttle signal to the engine speed controller whereby the engine speed is controlled; the vehicle speed limiter comprising a vehicle speed sensor (15) to obtain a signal indicative of vehicle speed; a GPS system (30), operable to provide a speed limit applicable for a present position of the vehicle; a comparator to compare the speed sensor (15) output with the speed limit provided from the GPS system (30); a throttle signal modifier unit (23) acting on the output of a throttle signal unit in use when fitted in conjunction with a vehicle throttle system to modify a generated throttle signal so t