[Christ]

If there is 10% ethanol in your fuel, and you remove it, isn't that the same thing as paying 10% more for your fuel? *You're getting 10% less burnable material for the same price...*

So lets say gas is $3.00 per gallon right now, and you have a 10 gallon tank... you need approx 11 gallons to make a full tank if you "wash" it, so you have to spend $33 as opposed to $30, a difference of $3, or one full gallon of gasoline with 10% ethanol added.

So you spend $33, and you get 10 gallons out of it (assuming you flush your byproduct), so you're now spending 10% more for your fuel than everyone else... If your mileage doesn't increase by at least 10%, it's not worth it to continue.

Of course, this doesn't take into account whether or not you pay for water (the negligible amount to wash the fuel, and the gallon or so to flush down the toilet), and sewer (because you flushed the toilet.. some people get charged for water in and water out.), either.

Ethanol boils at 173degF, so it's quite possible to separate the fuel in either a flask or a vacuum chamber into vapor, then condense it into another container, leaving separated water and ethanol, but the BTU required to separate the fuel from the water is probably going to end up being more than the fuel would return.

Sulfur dissolves into ethanol, creating a solid fuel pellet which can then be stored and separated or burned directly. Sulfur does not mix with water at any temperature, so it could be used to cleanly separate ethanol from water.