gasoline

Gasoline additives ensure that a car's engine runs properly. Otherwise, the engine will knock – and you'll be knocking on your mechanic's door holding a whole bunch of your favorite dollars. But researchers have figured out how to make isobutanol, an excellent gas additive, from beer. Here's the heady chemistry – and it goes down smooth.
When you are buying gasoline with a particular octane number, joke's on you. There is little or no octane in there, because octane will blow you engine up. A little primer on anti-knock additives. They're not so great either.