I'm getting 15 as well around town. Easy 21/22 cruising at 75 not pulling hills much. Only mod was Bilstein adjustable in the front at one below the max. I have a Tonno Pro cover but it didn't make any change in mpg.
My 13 RCSB with 3.55's easily pulls down 23 at 75mph,have seen over 30 cruising back roads at 45/50 mph.
Even in the city it pulls down 19/20 if i drive it decent
Mods are Magnaflow catback dual exhaust / ported and knife edged 78mm throttle body / Airraid CAI / Mopar tonnue cover / 2" suspension drop front and rear/ Redline synthetic oils in motor and diff.
I also run the tires slightly over their max pressure.
2012 QC 4.7
i get anywhere from 12-15mpg on my drive from home to work it sucks but ive come to live with it i think its cuz i have a heavy foot when i went on a long trip to colorado i got 25MPG for a full tank i thought it was magic.
I do a lot of city driving and I was still able to keep around 15-16. I bought a super tuner and getting 16-18 now. Well worth it on the 4.7 engine to go with superchips. It also depends on how you drive. I could see getting 11-12 if you're constantly on the gas. I went from a 26+/gal v6 accord to the ram. I pay attention to my rpm and only get on it when I need to. At least I try. :-)
You only live once so try everything at least twice.
Buy Once, Cry Once.