Ivoryhemi, that 21 MPG figure for a 5.7 with 3.92's is amazing.
I know that every driver is different, and everyones definition of "highway" is so different that it's basically a meaningless word, but that dash shows you did 66 MPH and averaged 21 MPG.
I ran my truck on an empty highway at 65 MPH and and over a fairly flat 20 mile stretch, I got around 16.5. My overall average on the 5,000 miles I've driven to date is 16.
I drive it like a grandma around town just to see how high I can get the MPG's, but it's never able to maintain anything much over 16 MPG. I never expected to get the mileage posted on the sticker, but I did expect to get more than the 2010 F150 I traded in.
It's a nice truck so far, and it's fun to drive.
Update...I just took my truck out to see what speed I'd have to drive to get 21 MPG, and the answer is 45 MPH. If I'm going 45 MPH, Ivoryhemi's 5.7 with 3.92's can pass me going 44% faster and be getting the same fuel mileage as me. Something ain't right about that.