I recently drove from NH to FL. Display showed 25 mpg between fill-ups and hand calculated was actually 24. 23 mpg with heavier tires sounds about right to me.
There is one on here that brought his oem driveshaft assy to a shop and got it re-phased and re-balanced and said it fixed his vibration issues. The only thing is that his truck was lowered.
Picked this up back in Aug. Kind of an oddball.... Lariat sport package with locker, and no tow package. I added a 7500lb rated hitch for $113. Rides smooth, good power, good gas mileage, decent electronics, good daily driver for the most part. Biggest complaints: Take off shudder, slip...