We are on our return trip from PA to California with our new 2010 Dodge Ram. Our mileage is currently 8100 miles. One the way out our gas mileage was not as good as on the way back. At this point with under 9000 miles.... we are getting:
towing - 8.8-11.4mpg our camper is about 6,000 lbs.
non-towing 15.2- 19.6 mpg
we are VERY happy with these rates!! And we love our dodge!!!

 

That's really good for a truck. I just purchased my 2010 Ram Sport Quad last week. It only has 154 miles on it. So far the best I have seen is 12.4 with just about 40 hwy miles. I purchased mine for towing a light weight 5th wheel. I am hoping my mileage improves a little bit.

 

400 mile round trip mixed flat land and moderate grades at 70MPH.

19.7 avg. (22.3 when tucking in a couple car lengths behind a semi.)

MDS stayed on constantly when in the semi's wake. 3.55 gears and stock 32.4" tires.

 

We did not get great gas mileage when we first purchased the truck. It was an average of 12 to 13mpg. The gas mileage increased as the mileage on the truck increased. It greatly improved after about 5,000 miles. We just purchased the truck in December in anticipation of this cross country trip. She is quite broken in now and running wonderfully!!! She has tackled every mountain without sweating, and not ever working as hard as she can. We had a 2000 Dodge Ram that had difficulty pulling the same camper up any hill. Dodge made some great improvements in terms of towing abilities!

 

Did you reset the computer when you left the dealer? The truck may have been test driven because your mpg's dont make sense for hwy driving

 

Hand calc'd I get 12-13 in city only, 15 mixed and eeked out 19 on a recent 400 mile round trip highway only. I cant complain about that for a 4x4 pickup.