I bought a brand new 2013 fx4 f150 3.5 v6 ecoboost two days ago. When going 60 mph for 20 minutes I was getting 17.1 mpg average! Where is the 20-22 mpg average that everybody is talking about? This vehicle is fully loaded but stock as well I have not done anything to it. Does the gas mileage get better after you get "x" amount of miles on the truck.