Abstract: Entirely mechanical assembly attachable to accelerator pedal of motor vehicle for selective setting of fuel flow. Chosen setting can be instantly overridden by pedal depression or be completely cancelled by tapping brake pedal. Set position is determined by longitudinal series of transverse slots on lengthwise-reciprocable control shaft, which slots are engagable by unidirectional latch; latter is disengaged by small rotation of shaft to bring smooth surface of shaft to sliding registration with latch. Cable connection between brake pedal and control shaft converts vertical movement of pedal to rotational movement of shaft.