Abstract: The passive energy saving device, disclosed herein, may be integrated directly into or added to the exhaust system of an internal combustion engine, to increase the system's fuel efficiency, by acting to reduce the overall backpressure of the total engine and exhaust system. It is a well known fact, accepted by those knowledgeable in the art, that a reduction of exhaust backpressure generally increases the overall fuel efficiency of an internal combustion engine. This passive device consists of a generally funnel shaped outer housing which is open at both ends, and surrounds a smaller diameter, cylindrical exhaust extension tube, which passes longitudinally, on the inside, through the center of the funnel. When airflow is introduced into this funnel, a resulting pressure drop, at the small end of the funnel reduces the backpressure on the vehicle's exhaust system. The net result of the lower exhaust pressure is the increased fuel economy of the vehicle.