Abstract: The specification discloses a linear actuator including a quick-release mechanism enabling the actuator to be successfully commercially utilized in a variety of applications including a vehicle speed control. More specifically, the actuator includes an axially reciprocable rod, a mechanism for angularly shifting the rod about its axis between first and second angular orientations, and a quarter-turn coupling for releasably coupling the rod to an element, such as a throttle cable, to be driven thereby. Angular shifting of the rod couples and releases the rod and driven element through the quarter turn coupling. Also disclosed is a vehicle speed control responsive to vehicle acceleration and/or vehicle tilt to deactivate the speed control when either the acceleration or tilt falls outside of acceptable parameters.