Iv'e hauled both hard and soft side my truck is a 2000 Dodge ram 3/4 ton full size ext. cab with a cummins diesel six speed manual tranny, with out a camper on my truck I get 21 MPG at 73-74 MPH with either of these campers my mileage dropped to 15.5 at 73-74 MPH, the hard sided camper weighed...