Pop-up camper and fuel mileage

[Regcabguy]

I'm getting 20.5 with a 2003 Dodge Cummins H.O. and FWC Grandby. These are mostly highway miles at 60-65 mph.

The truck is quad cab, long bed, 4WD, 6-speed manual, 3.73 axle.

The FWC is raised a couple inches above the bed/cab, so maybe the MPG could improve by lowering it or adding a fairing.

The '03-'04 HO's typically get 1-2 mpg more than the '04.5-'05's due to one less injection event and lower hp,but 20.5 with a FWC is amazing. Keep that truck as empty ones rarely get that much.