87 octane gasoline, often called "regular" gas, is one of the most commonly used fuels in the United States. But what gives it that 87 rating is a word you've probably heard a time or two: Ethanol.

Folks have been experimenting with ethanol in modern combustion engines even when they weren't so modern. Nicolaus Otto, the inventor of the traditional four-cycle engine, used it to power one of his ...