[Honda100]

Back in the states I had a Range Rover 4.0L V8 that would constantly get 24.5-26 on the freeway at 57 mph cruise. Drag coefficient was .31 and I usually would lock the truck in access mode (low down). I know, apples and oranges, but I mean to chip in regarding the drag coefficient and aero mods, because if a Rover V8 (some of the worst mpg engines I know of) 2.5 ton SUV can do 25, I am sure your Ranger can easily match it. While old tech, the Cologne motor is a decently efficient one so I believe there's a lot of untapped resources regarding aero mods.

Also, I had a 4.0 Ranger 4x4 and never did reach 20 mpg....or 18....or even 17. I think 16.7 or 8 was my best tank, but that was a construction truck that was always hauling stuff. Anyway, I think you're doing well. Sorry to ramble.