I have always operated under the assumption that since gasoline weighs about 6 lbs/gallon, and a full HAH tank weights over 100lbs, one would get better gas mileage as the tank gets near empty due to the weight loss. I was then looking in the database and noticed that a lot of people fill up less than 10 gallons. Has anyone noticed if their mileage does improve at the end of a tank as opposed to a full tank?