Pick your potion: hybrid, hydrogen, electric, diesel, ethanol, flex-fuel or gas. Confused? Here's a rundown of alternative vehicles and their fuels.
Hybrid: Using a gasoline engine paired with an electric motor, hybrids score among the highest on greenest car lists. Examples include the GMC Yukon SUV, Honda Insight and Civic GX fleet sedans and Saturn Vue SUV.
Electricity: Running on batteries that are recharged either at home with a company-supplied charging device or at designated gas stations, vehicles include GM's upcoming Volt and Daimler's Smart Fortwo Passion. The infrastructure for recharging is still limited, but the all-electric nanotechnology in the midsize, four-door Phoenix pickup has a range of 130 to 250 miles per charge and needs just 10 minutes to recharge to 95 percent capacity with an offboard charger or six hours onboard from a 220v plug-in.
Diesel: Made from petroleum but no longer belching black smoke or powering noisy engines, diesel is clean, clear and quiet in Audi, Mercedes-Benz and Volkswagen lead-diesel engine vehicles. Other diesel vehicles include Dodge's Sprinter van, GMC's Sierra turbo-diesel pickup, Jeep's Grand Cherokee SUV and Toyota's biodiesel Land Cruiser SUV.
Natural gas: Honda's popular fleet sedan, the Civic GX, runs on natural gas and can be filled at designated gas stations or from a home refueling appliance. Some states offer benefits to drivers of natural gas vehicles, including carpool lane access, insurance discounts, tax credits and free parking.
Ethanol/Flex-fuel: This biofuel is made from grain. The vehicles run on a mix of 85 percent ethanol and 15 percent gas. With 2 million flex-fuel vehicles already on the road, GM is ethanol's greatest champion, offering 11 different flex-fuel models--most, like the Uplander cargo van, at no extra charge for flex-fuel capability. Other choices include vehicles from Dodge, Ford, Mazda and Nissan.
Hydrogen: GM's Equinox and Honda's FCX Clarity have water-generated, hydrogen fuel cell-powered engines. Their only emission is vapor. Shell Oil's hydrogen division is serious about this alternative fuel's potential and expects hydrogen vehicles will be more fully developed within six years. BMW's Hydrogen 7 sedan was introduced last year in limited availability. It's based on the 7-Series and can run on gasoline or hydrogen, which is sold as compressed gas at refueling stations.
Gasoline: Several gas engine vehicles rank as ultra low-emission or partial zero-emission vehicles by the American Council for an Energy Efficient Economy. They include the Ford Focus, Honda Odyssey van and Ridgeline pickup, Mazda MX-5 roadster, Nissan Sentra, Toyota Corolla sedan, Volkswagen Jetta and Volvo V70.