Not challenging the idea, but just did a quick google. Per at least one "find cheap gas" site the price in the Valley is about a dime per gallon more right now, $3 and change versus $2.90 and change. I think most people prize convenience more than a few cents savings, so going out of one's way to find those savings which may not add up to even $10-20 year may be more trouble than it's worth.

Without commenting on the tax itself, the math may work out. I dunno.