new dodge 1/2 ton diesel

I don't see how they get 27 MPG.

I drove my girlfriend's uncle's 2009 2500 Megacab truck with the cummins in it on a road trip and I got 43 mpg. I didn't believe what the indicater was reading so I checked it, I actually got 44 MPG! And the the truck is bone stock.
I find this very hard to believe since I own a 2010 Ram megacab with a cummins and on its best day gets maybe 17 mpg. 2009 Rams had Bluetec system ( dpf,egr and cats) on them and even if all that was deleted the best it would get is low to mid 20's. These truks weigh almost 8000 lbs. Vw rabbits barely get this type of mpg. :protest: