I'm getting 23 MPG empty right now with only 8000 miles on the odometer. I think my wife got about 15 pulling 10,000 down to Alabama when the truck had only 6,000 miles on it. The engine is no where near even starting to break in, so the economy will only go up from there. With at least the Cummins the sweet spot for fuel economy is at or below 2000 RPM.
2006 Dodge Ram 3500 Mega Cab w/6-Speed T-56 Tranny. Completly stock.