The world needs a new source of energy, an unspillable source.

Does biofuel with 10% ethenol get the same gas mileage as regulare unleaded fuel?

I filled up with it once feeling good about my descicion. The lady at the station said that an average American using only unleaded biofuel would save a barrel and a half of oil per year, but it seemed like I may not have had as good of gas mileage, which means I’d have to fill up more often, counteracting the saving of oil. Can anyone give me any information on this?