Abstract: The invention relates to a speed limiting device for a vehicle driven by an internal combustion engine provided with a twin-body carburettor or a dual fuel injection unit comprising two throttle butterfly valves controlled by the vehicle's accelerator pedal through an operating mechanism, a flexible connection mechanism combined with at least one of the said throttle valves and a depression valve calibrated at a given depression value corresponding to a vehicle speed not to be exceeded and designed to operate, above the said given speed, in the direction of closure, at least one of the said throttle valves combined with the said flexible connection means.The flexible connection means (3-7, 15) is placed between the said throttle valves (P.sub.1, P.sub.2), one of which (P.sub.1) is controlled by the movements of the accelerator pedal, and comprises a spring (6) of the right stiffness to lock the said throttle valves (P.sub.1, P.sub.