A diesel engine is paired with a six-speed automatic gearbox. This combination is enough for hauling 4,300 lb. of cargo and towing 7,500 lb.Massive Transit 350HD High Roof Diesel reaches fuel economy of 21 mpg which is an outstanding achievement considering it has the aerodynamics of 35-floor building. With this fuel economy, Kingclima Transit is maybe the best mpg cargo van at