I agree about this "superior mileage" some of these guys claim they get from the F6B. Must be coasting downhill with the throttle closed, a tailwind, and rider weighs about 150lbs...I have never really watched the mileage thing as I personally don't care about it..If a sudden drop happens then I would check, but otherwise a waste of time in my opinion...At 77 years old I don't ride like a crazy man, but still "get-on-it" once in a while, but mostly conservative riding and don't think I have ever gotten over 40 mpg....Ride safe