Well I've had the truck for 6 months now and absolutely love it. Here is what I've been getting for mileage for the last month or so. All around driving with the following.
60% - city/back roads
30% - towing
10% - highway
I do not think these are bad numbers at all considering my wife tells me I always have my foot in the turbo's.

 

Not bad IMO - I also get 18-20 running around on 2 laned back roads and around 16-17 running 75-80 on interstates. When I hook up to a trailer my mpg drops to around 10-14 depending on how fast I am driving. My life time mpg is @ 16.8 since last November. Mp

 

I had a trip last Sunday night 192.6 miles mostly hw driving with a 14' enclosed trailer with approx 1500 lb payload. MPG was around 10.6 average speed 70-75 mph Maine turnpike. Truck has 900 miles on the clock after the trip here at the shop. No sway, no problems and lots of power no worries on the towing part....