Recent round trip to Alabama from Illinois was 99% interstate driving,920 mi.Used cruise whenever possible. Lowest instant milage was 19,best was 20.5. I set cruise at 70 mph. I have a 2011 f150 sc,4x4,5.0,3.73 gear. My intown average is 17 mpg. Milage has improved since 10,000 mi. and has probably peaked.