It used to be that cars just ran on gas. And not premium unleaded with a proprietary blend of cruelty-free, hypoallergenic, antioxidant detergents. Just plain, old... gas.

Not anymore. A growing number of today's cars can run on E85, a mix of ethanol and gas. And diesels can run on regular diesel, biodiesel or, if you've got time, some money, a bucket of parts, and a warranty to kill, even straight vegetable oil.

Until manufacturers figure out a way to power cars on compost, rocks and discarded junk mail, those are our choices.

Are any of them right for you? What are the risks and benefits?

We've got all the answers... or, at least, some of them, right here.

Tom and Ray Magliozzi
aka, The Crude Brothers
Click and Clack, the Tappet Brothers