Considering our planet's dwindling, non-renewable oil reserves, Greasecar kits, and others like it, are worth investigating. Willner refills his petroleum tank less than once a month, and his vegetable oil comes from the Dwight-Englewood School cafeteria in Englewood, New Jersey, which supplies renewable reserves of used oil for free. Good for the earth, good for the wallet. In fact, since he bought the car last September, he says his total fuel costs have been "a bit less than a hundred dollars."

Greasecar's Michael Garjian says that using straight vegetable oil for fuel can lower greenhouse gas emissions by nearly 100 percent, greatly reducing air pollution. And, he adds, "It's carbon neutral. When you burn vegetable oil, the gas contains carbon dioxide, but it's the same carbon dioxide...that was absorbed by the plant while it was growing."