Link to video Even with 3.92 gears is got great mpg - 33+ mpg at 65 mph :E. Also of note was the EVIC mpg was low compared to actual, just like the other Ram trucks they tested.
I own a 2014 EcoDiesel with 3:92 gears, Crew Cab, 6'4" bed with 4x4. The MPG I get is 26.5 on the open road, that is from two 2,000 mile trips, and 19 mpg around town. Towing a TT at 7,200 pounds loaded I get 14 MPG.