Abstract: The speed of an automobile is limited by a throttle controller between the gas pedal and the throttle valve. The controller is actuated by a digital or analog processor in a speed limiter control module. The speed limiter control module receives vehicle speed and has a maximum speed input device such as a keypad and a readout display panel which indicates the maximum speed set. When the vehicle speed exceeds the set speed, the throttle controller disengages the gas pedal from the throttle valve to prevent the gas pedal from causing further speed increase. The speed limiter control module is lockable so that only authorized persons are allowed to reset the maximum speed. This allows the owner to preset a maximum speed and loan the automobile to his offspring or others knowing that they will be speed limited. In the same manner, maximum acceleration and/or engine RPM can be preset and controlled.