Well my F-250 is a little older. has the 5.8 2WD with a Knapheide utility topper, which is a heavy topper, plus I carry a lot of stuff. I averaged around 9 to 11 MPG city. Don't forget you can't really compare mileage between a 150 and a 250, the 250 is heavier and geared lower. Plus with 4x4 I am guessing you will be lucky to break 10 MPG if it is loaded.
Of course the 250 is for sale now, I got a new 1 ton van with a high top Royal body. Never bothered to ask the salesman about MPG, what does it matter? The way I see it, the customer pays for the fuel anyway. As it turns out it gets 8.6 MPG right on the nose every time.
