I recently made a 352 mile trip on relatively flat state highways and secondary roads in MI with some small hills. I was cruising at 1500-1600 rpm and I got 21.95 mpg using 16.04 gallons. When accelerating I never let the motor see over 1800 rpm because I had a cargo in the bed for 80% of the trip (up to 600#). The truck is still stock other than a PPE tow tune, blocked EGR and PCV reroute. I still have the stock intake, exhaust, ect. Towing a tall 32' long enclosed trailer at 22-23k combined I get 9-11 mpg at 75-65 mph.