Started from LA to Ohio 2800 miles with empty Sunrader and got 23 MPG at 35-40 mph down to 17 mpg at 55-60 mph. Then fillup with one ton of personal effects and went back to California and average 19 mpg at best at 40 mph. Then axle (5 bolt ) broke and another 1300 later the used one ton (6 bolt) now works.
Jeff