Abstract: A vehicle engine throttle valve control device (10) is applied intermediate the vehicle operator's accelerator pedal (14) and the engine's throttle body (12) to selectively override or modify the operator's ability to control vehicle/engine speed and to assert independent control thereof as a function of various input parameters (49,50,52,54). Linkages (26,28) interconnect opposed ends of an assembly of half levers (21,23) with accelerator and throttle. The half levers rotate upon a pivot (20) which is selectively displacable to effectively shorten or lengthen the linkage in response to an operator independent signal from a control circuit (42). A half lever stop (27) fixes the relative positions of the half levers whenever the throttle body is in an off-idle position.