While my 06 was in the shop for a month, I had a 2014 Ram 2500 CC 4x4 as a rental from Enterprise (grocery store was paying for it, as a cart blew out in the road and hit my truck). Over the course of the month I had their truck, I pulled a hand-calculated 21.5 mpg combined. Picked the truck up with 1,2xx miles on it, turned it back in with 2,7xx. Always drove the way I drove my 06 (kept it out of OD on the back roads under 50 mph). Obviously, since it's a rental, all the enviro-nazi gear was in place.

If you drive them conservatively, they'll do it.

Caveat: I burned thru half a tank of DEF in that 1500-ish miles, and the tank is "supposed" to last approx 5000 miles. No biggie, when the local Pilot station had it at the pump for $2.35/gal (about half the price of the gas station gallons).

Really??
 

I average 19 and 20 on lots of trips in the first 5000 miles however I doubt your overall is 21+ mine clearly says 16.7 overall