2013 Ford F250, 6.7 Diesel, Suggestions to improve mileage.

2012 F350 CC DRW 6.7L, 3.73 axle, towing 18,000# and we get 9 to 10 mpg at 63 mph. Unloaded on the highway at 65 mph, 15.5 to 16 MPG. mixed highway and city, we generally get 13 to 14 mpg at the lowest. Lowest fuel economy was a 20 to 25 mph head wind and we dropped to 7.6 mpg, but had no problem maintaining 63 mpg.

If the OP is getting 11.8 mpg unloaded, he either has an engine problem or a really heavy foot.

Ken