Been averaging 43 mpg combined. (About 1/4 city to HWY ratio. Drive through town, then 10 miles of hwy to work. Pure HWY has been yielding 60 mpg. I think altitude has a role in this.
Cut the cd in half though.
Aero topper made of polycarbonate, tapered at 11.8 degrees. Approx 3-4mpg increase
Full Boat tail, extending at 12 degrees on all sides, 5 feet behind the tailgate, on a hinge, and easily removable.
Rear Wheel skirts approx 2mpg
Front wheel arch gap filler, approx 1mpg
Front 1/3 belly pan approx 2mpg
One side view mirror folded in, approx 1 mpg
Mooncaps, approx 1.5-2mpg (horrendous shape w/o)
Partial Grill Block, approx 1-2 mpg
Nut behind wheel slightly adjusted, approx 4mpg
All relevant at hwy speeds where I'm in the mid-40s, in town my mpg are mid-20s.
Planned Mods:
Engine block heater. Hoping for 1mpg
Full belly pan. Hoping for 2 more mpg
Better rear wheel skirts. Hoping for 1 more mpg.
Remove AC, hoping for 1 mpg
Remove altenator
Full frontal deflector, removable plexiglass sheet from top of cab to past hood.
I think 70+ mpg is possible at this altitude, maybe 65+ at sea level but have no idea on that.