I have a Lariat, 4x4, 5.5' box, 3.55 gears. No tonneau yet, but my Bakflip G2 will be getting delivered any day now.
I've had the truck for 10 days, and just rolled over 1,000 miles. With my city/highway commute, and a fair amount of time warming up, I'm getting 15mpg. Of course, that includes getting into the turbos pretty good a few times each day. On a 150 mile trip last weekend, I got 19mpg, but there were a lot of stop signs. I have no doubt that I will get upwards of 22mpg once it is broken in, and the temps warm up. The computer is off by at least 2mpg.
The truck REALLY woke up after 500miles, and it seems like there was another big jump up in performance around 950-1000 miles. It would be interesting to see if Ford has them detuned for break-in...
I came from a 2007 5.4l with the same configuration, and hadn't seen over 13mpg since November. My average was probably right around 12.5. That will sound low to people, but at -20 or -30 it's nice to let it warm up for 10-15 mins!