An apparatus for controlling a motor vehicle, including a fuel cutting device for cutting a fuel supply to an engine while a throttle valve is placed in an engine idling position, a clutch control device for effecting partial or full engagement of a lock-up clutch disposed in parallel with a fluid-filled power transmitting device while the throttle valve is placed in the engine idling position, an automatic cruising control device for controlling the throttle valve so that the vehicle runs at a substantially constant speed, and a restricting device for restricting or inhibiting the engagement of the lock-up clutch by the clutch control device while the throttle valve is controlled by the automatic cruising control device. The restricting device may be adapted to restrict or inhibit the engagement of the lock-up clutch if it is determined that the frequency at which the throttle valve is alternately placed in the engine idling position and a position near the engine idling position is higher than a predetermined threshold.