For the complete story on E85 and ethanol visit AutoGuide.comAutoGuide’s regular “Under the Hood” segment has already explained the vagaries of octane and the advantages of Top Tier gasoline, but there’s so much more to fuel than that. Ethanol, for instance, is a major component of gas, and something that’s a potential peril for consumers. But what is ethanol? And what is E85? Should you run these fuels in your vehicle?