Just completed 1800 mile journey in our "new to us" 2011 Fleetwood Expedition 36M from Dayton, OH to Phoenix AZ, ISB 6.7/MH-3000 360HP/800ft-lbs (approx. 27.5K weight) averaging between 8-8.5 MPG(depending if you calculate Generator usage) cruising 65 MPH/1800 RPM.