Abstract: A system for controlling the speed of a vehicle featuring a throttle valve controlling a feed device on the vehicle and counteracted by an elastic return spring. The system consists of an electromechanical actuator designed to generate a torque as a function of its supply voltage; and an electronic control unit connected to a speed sensor and designed to vary the supply voltage to the actuator. The actuator operates an arm connected mechanically to the throttle valve via drive elements, and is designed to generate on the throttle valve a predetermined torque capable of counteracting that generated by the elastic return spring subsequent to rotation of the throttle valve via operation of the accelerator pedal on the vehicle.