lol
The above mileage was calculated while it still had the awful exhaust and a stock Hitachi carb jetted to run too rich all the time for the thermal reactor to get a rich enough mixture to burn completely and all that. Since then I've gone to a collected RB header and a single 2" free flow system with a Camden. The exhaust is far too small for high RPM use (gonna redo it in 2.5") but the Camden can be driven in such a way that it improves mileage over the stock carb.
So if I had to guess what its mileage will be after the free flowing exhaust is installed, and the new engine, with the Camden, I'd have to say probably in the neighborhood of 15 mpg. Remember it's a heavy vehicle with a somewhat low geared rear end.
I did recently swap over to a light steel flywheel though, which acts like less unsprung weight, for a minor improvement is gas mileage.