What kind of fuel mileage will a 2WD F-150, 300 6cyl. with a manual transmission get on average? Does it get 20mpg?

I ask only because I bomb around in an old Ranger to keep miles off my good truck and for better fuel mileage. I wonder because I would rather have a full size if I knew I could get 20mpg with it.

 

My dad gets around 16-17 around town, and has gotten I think around 22 or so on the highway. He has 2.73 rear gears too, which helps with highway mileage.

 

on my last trip, which was 700 miles, i got a best of 22.4 mpg. that was mostly 65mph country highway driving. my truck is a 300-6, M5OD manual tranny, and tall gears in the back, im not sure what they are yet, but they have to be 2.73 or 3.08s.

i burned one tank driving about 75 the whole way, and got 17.5 or so mpg.