Going bio with your auto doesn’t mean you have to invest in some strange contraption your neighbors will stare at. In fact, upward of 4 million cars currently on the road in the United States are already compatible with E85, a blend of 85 percent ethanol and 15 percent gasoline. More automakers are making new E85-ready models — known as flex-fuel vehicles — every year. To top that off, so to speak, any gasoline-powered car can run on a 10 percent ethanol/90 percent gasoline blend — in fact, the state of Minnesota requires that all gasoline sold there is of that balance. Some folks even elect to run their regular ol’ cars on blends as high as 30 percent, but most auto manufacturers only guarantee their warranty services on non-flex-fuel cars for up to 10 percent blends.

Put that in your tank and combust it.

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If you’d rather have your fly ride be fry-powered, just about any diesel carriage can use biodiesel. For the more ambitious, diesel cars can also be converted to run on straight vegetable oil. (See Umbra Fisk’s advice for converting your car to run on veggie oil.)

Fuel of Choice: Ethanol

The National Ethanol Vehicle Coalition and the U.S. Department of Energy have handy, searchable lists of cars and trucks that can run on E85, and the American Lung Association’s Clean Air Choice campaign lists ’em too.

They’re roughly the same lists, from different perspectives, but one thing is clear: the cars that are best equipped for E85 — which has caught on in a major way with industry and politicians in the U.S. — are made in the U.S.A. Coincidence? Discuss.

Companies with models that can use ethanol: DaimlerChrysler, Ford, General Motors, Isuzu, Mazda, Mercedes, Mercury, Nissan.

Fuel of Choice: Biodiesel

Check out Biodiesel America for a listing of new diesel cars in the U.S. Grassolean offers a list of biodiesel-ready autos as well, though it’s reader-built and somewhat scattered.

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Although biodiesel doesn’t have the heavy backing in the U.S. that ethanol does, any diesel engine can use biodiesel, making the options somewhat broader.

Companies with models that can use biodiesel: Audi, BMW, Chevrolet, DaimlerChrysler, Ford, General Motors, Isuzu, Land Rover, Mazda, Mercedes, Mitsubishi, Nissan, Peugeot, Saab, Toyota, Volkswagen, Volvo.