Just for comparison:
2001 F350 Crewcab DWD Diesel (International) with Arctic Fox 1140 (5000 lbs)
Trip to Northwest (Glacier, Yellowstone, Tetons etc) from Jersey in summer/fall 2014:
6276 miles - 481.5 gals Diesel (3.70 to 4.20 /gal) = 13.03 m/gal
or $0.29 / mile ($1850.24 total fuel cost)
Trip on east coast (New Brunswick to Atlanta et.al)from Jersey in summer/fall 2015:
3981 miles - 299.4 gals Diesel( 2.09 to 3.10 / gal) = 13.3 m/gal
or $0.18 / mile ( $711.98 total fuel cost)
Ask me how happy I am Diesel is way down!!!! Enjoy the ride.