Did you know that in the U.S., cars are responsible for almost a third of all greenhouse gases emitted into the atmosphere? You've seen the latest Pimp My Ride, you've been following the 12-step Break the Addiction program, and you know that climate change is real. So what are you waiting for? It's time to pimp your ride eco-style!

The best way to be good to the planet while you drive is to reduce your car's output of CO2, the main culprit of global warming. One way to cut your carbon output is to tank up on biofuel, which is any fuel made from plants. Adding some green to your custom machine is as easy as pulling up to your local KFC and asking for some used fryer grease. Really! If you're driving a car that already runs on diesel, all you need to do is make some minor engine conversions or simply thin out that old fryer grease, and you too can run your car on vegetable oil! If you want to make the plunge from diesel to biodiesel, check out Greasecar where you can pick up a do-it-yourself kit to convert your car for a couple hundred bucks.

If you don't want to be up to your elbows in grease, you can always buy a ready-made biodiesel blend at your local gas station. B20, which is a widely available blend of 20 percent biodiesel and 80 percent gasoline, can be used in almost all unmodified diesel engines. Another alternative fuel that is gaining in popularity is ethanol. It's alcohol-based - but not the kind you make a Martini with. Ethanol is made either from crops like corn or wheat, or from "cellulosic biomass," a.k.a. grass and trees. You can already run pretty much any car on a 10 percent ethanol mix, but if you want to top your tank with a more potent blend, you gotta drive a flexible fuel vehicle.

You could also tank up on natural gas, which has lower CO2 emissions than gasoline-mixed biofuels. Again, you can't just fill up your mom's old Taurus with the stuff - it has to be a natural-gas run car. If you're going to go ahead and buy a new ride, consider going hybrid. Hybrids are cars that run on two power sources, generally gasoline and electricity. They cut carbons and save you money at the pump due to their great gas mileage. Remember though, no matter what you run on, you'll still release greenhouse gases into the atmosphere - so biking, skating, and walking are always the best zero-emissions options.

There are other ways to reduce your carbon footprint as well, which don't involve buying new wheels or getting a green custom job. By getting your car serviced regularly (clean air filters, anyone?) and checking your tire pressure, you can improve your car's mileage by 10 percent. And if you roll at 50mph instead of 70, you'll get 50 percent more miles to the gallon! Take these steps, and you won't be the only one riding clean...Governor Arnold Schwarzenegger of California passed a law last year that requires CO2 emissions in the state to be reduced 25 percent by the year 2020. So follow Arnold's lead by pimping your ride green, and saying hasta la vista, CO2!