I completed a 1,119 mile round trip from NW Arkansas to Sioux City, IA. 2003 35' Expedition with the 5.9L 300HP Cummins
9.4 mpg for the entire trip
First 374 miles with a tail wind - 10.7 mpg
Last 745 miles with a head and cross wind and some hills in North Central Iowa - 8.8 mpg
When on the Interstate highways, cruise control was set at 71 MPH.