ethanol has about one-third less energy than an equal volume of gasoline

See Root Cause of Ethanol ‘Blend Wall’? Consumers Don’t Like Rip Offs by Marlo Lewis of globalwarming.org. Excerpt:

"Although ethanol is cheaper by the gallon than regular gasoline, ethanol has about one-third less energy than an equal volume of gasoline. On an energy-adjusted (bang-for-buck) basis, regular gasoline is almost always the better buy than ethanol. Consequently, the higher the ethanol blend, the worse mileage your car gets, and the more money you spend to drive a given distance.

FuelEconomy.Gov, a Web site jointly administered by EPA and the Department of Energy (DOE), calculates how much a typical motorist spends in a year to fill up a flex-fuel vehicle with either E85 or regular gasoline. The exact bottom line changes as gasoline and ethanol prices change. The big picture, though, is always the same: Ethanol is a net money loser for the consumer.

At today’s prices, depending on make and model, it costs an extra $900, $1,200, $1,600, or even $2,400 annually to run a flex-fuel vehicle on E85 rather than regular gasoline. Those hefty price differences — not oil company machinations or EPA indecision — are the principal barrier to market penetration of E85 and other high-ethanol blends.

Even if everybody owned a flex-fuel vehicle, and every service station installed E85 blender pumps, few willing customers would buy the fuel. Lower energy content, inferior fuel economy, and higher consumer cost are the root cause of the blend wall. The same factors also explain why the ”choice” to buy ethanol must be mandated. After all, if ethanol were a great deal for consumers, why would we need a law to make us buy it?"