2017 Forester 25' class C with the Ford V-10.. we saw 10 mpg one time after driving 55 mph on a flat two lane road for several hours. Generally it drops 1/2 mpg for every 5 mph over that.. so 60 mph = 9.5 mpg, 65 mph = 9.0 mpg, 70 mph = 8.5 mpg. This is for good conditions, deduct more for...