the ethanol that's added to gasoline is supposed to reduce emissions by 20%..
BUT.. the mileage is reduced..
i get 200 miles from a tank with ethanol, and 300 miles from a tank  WITHOUT IT..
if you need half again as much gas, just to get to the same point, it ends up putting 20% MORE EMISSIONS into the atmosphere..
plus, you're paying 6 bucks a gallon, instead of 4..
PLUS, it messes up your engine.

i sent "the math" to all the branches of the epa, a few yrs ago.. they don't care..

the warmongers don't WANT to give up their grip on your nuts..
they'd rather the planet go down in flames..

also, going 70 miles an hr, vs 50mis/hr, uses upwards of TWICE AS MUCH GAS..
(in MY car, at least..)
when i noticed the HUGE difference, i immediately ceased driving that fast, so the numbers aren't very accurate..
i think it has something to do with "wind resistance".. the faster you go, the harder work the vehicle has to push against the resistance.. (so, it would vary according to the shape of your vehicle)