Yep. On its best days, my F-150 gasser (5.4 liter) gets 17 mpg.
My F-250 with the 7.3 liter PowerStroke diesel gets 25 mpg on the highway, and AVERAGES 20 mpg (and that figure is calculated from the total fuel I've burned since I got it -- 440 gallons, 8810 miles).