Abstract: The setting of a continuously variable transmission to a neutral range is detected as a neutral signal. A delayed signal which follows a change of this neutral signal is generated with a delay, and when this delayed signal indicates the neutral range, a target idle rotation speed of a diesel engine is increased. An exhaust throttle is provided to allow the exhaust pressure of an engine to rise in order to raise heating efficiency in the passenger compartment when a vehicle is at rest. By avoiding a delay period from the change of the neutral signal to a change in the delayed signal, torque shock due to the opening or closing of the exhaust throttle is reduced.