Picked up a grandpa truck in Salem Oregon yesterday and drove back to Montana 700 miles. It is a 2011 F250 4x4 6.2 V8 6 spd auto 3.73 rears and i got it for 20K less than what it would cost me to order the same truck today and it has only 52,000 miles on it. . I ran 70-75 MPH and I went from 200 feet elevation in Salem Oregon up I5 to Portland then 82 east to the Tri-Cities, then 395 North and steadily climbed to Spokane Wa. Elevation @2,000 feet and then over 2 mountain passes going east on 90, one at 3,100 feet (4th of July Pass) and one at 4,700 feet. (Lookout Pass) Then it was rolling hills and 65 MPH max due to deer and elk on the road all the way from St Regis MT up 135 to 200 to 28 to 93 to my valley which sits around 3,000 feet. Mileage was a LOT better than expected. Overall for the trip i averaged just under 55 MPH including around 50 miles total of town driving and the balance interstate and 2 lane roads. She averaged 14.6 MPG and this is coming from 200' elevation over 2 mountain passes home to my valley at 3.000 feet. Best i saw was once i got into Montana on a 100 mile stretch of reasonably level road where i saw 16.3 mpg with the cruise set at 65 MPG. BTW, Yes, i did check 2 tanks on paper and the trip odometer is spot on. Here are some pics I was also locking out gears on the hills and passes to keep it from shifting as well.............