Abstract: During a fuel cut-off control, if a vehicle deceleration rate becomes greater than a rapid deceleration determination value, which is calculated based on a rotational resistance of internal combustion engine 1, a vehicle is determined to be in a state of rapid deceleration. The rapid deceleration determination value is set to decrease as the rotational resistance of internal combustion engine 1 increases. The rotational resistance thereof increases as the vehicle speed decreases, and increases as a transmission gear ratio increases. Thereby, during decelerating on a high vehicle speed side, an erroneous determination of rapid deceleration due to a longitudinal vibration of the vehicle that occurs when the fuel cut-off control starts can be prevented, and during decelerating on a low vehicle speed side, a determination of rapid deceleration can be implemented to terminate the fuel cut-off control and thereby prevent the internal combustion engine 1 from being stopped.

Abstract: During a fuel cut-off control, if a vehicle deceleration rate becomes greater than a rapid deceleration determination value, which is calculated based on a rotational resistance of internal combustion engine 1, a vehicle is determined to be in a state of rapid deceleration. The rapid deceleration determination value is set to decrease as the rotational resistance of internal combustion engine 1 increases. The rotational resistance thereof increases as the vehicle speed decreases, and increases as a transmission gear ratio increases. Thereby, during decelerating on a high vehicle speed side, an erroneous determination of rapid deceleration due to a longitudinal vibration of the vehicle that occurs when the fuel cut-off control starts can be prevented, and during decelerating on a low vehicle speed side, a determination of rapid deceleration can be implemented to terminate the fuel cut-off control and thereby prevent the internal combustion engine 1 from being stopped.