In a perfect world the cost differential works in ethanols favour as itch cheap as chips to produce (except it's environmental benefits ae negatd by the processes used to make it).
But the world we live in is far from perfect. Big Oil, big energy, big supermarket and bg grubberment all know its not fashionable to carry pocket calculators, crunching numbers before you lay down your hard earned, so they screw us with their unpropertional profit margins. If any fuel is good for the environment or is a performance fuel, they will make sure it costs more to run, thus playing on your conscience.

At the endf the day. Who cares how much more you use, as long as it works out cheaper to run.
My car wastes 30% more lpg than it does petrol ydt the price of lpg at my favourite servo is only 40% of that for petrol. Now you'd be a fool for not using the cheap stuff if you use a little more of it.