Ethanol additive

If you go to a gas station. Gasoline usually has an additive of ethanol of 10%. Which it seems does not cause a problem with performance or economics of miles per gallon. So my question is what is the maximum percentage of ethanol additive would a auto perform. If we are looking for an immediate decrease in dependency on foreign oil, this seems an answer. if 12, 14, or 15% would work, That is a signficate decrease. Mike, Auburn Indiana

Right now the car manufacturers are worried that just such a thing might happen, because the cars aren’t designed to handle more than 10%. There’s no performance benefit, mileage is lower. And, in my opinion, there is very little reduction in oil imports because of all the oil used to produce corn. On top of that, it increases food prices (the Europeans are contemplating major reduction on biofuels becasuse of this, and the clearcutting of rainforests for biodiesel) and increases pollution from added fertilizer use. Not that you asked…

It depends on the car, but for some the 10% Ethanol very much does cause problems with performance and economics of MPG. The only reason why the economics sometimes work out now is that ethanol is heavily subsidized by the federal and most state governments making it artificially cheap.

But to answer your question, a regular car can’t handle much more than 10% ethanol, so inching up the mixture would probably start to cause problems. There are of course, flex-fuel vehicles out there that run on 85% ethanol and there’s not really any reason why cars couldn’t run on 100% ethanol (although I suspect this might be to stop people from mixing themselves cocktails at the gas pump). The trouble is that the energy content isn’t even close to gasoline, and flex fuel cars take a serious MPG hit running on E85, usually somewhere between about 25% and 40%.