Updated January 26, 2011 9:38 AM PST

Green car buying guide - CNET Reviews

by Wayne Cunningham

Flexible fuel vehicles

GM markets many of its cars as flexible fuel vehicles, meaning they can run on a fuel mixture up to 85 percent ethanol and just 15 percent gasoline, referred to as E85. Ethanol is an alcohol commonly produced from corn in the United States and sugar cane in other parts of the world. Ethanol is also widely used as an additive to gasoline. E10 is a mix of 90 percent gasoline and 10 percent ethanol, while E100 is 100 percent ethanol. Most cars can run on E10, and many state governments have mandated its use, as the 10 percent ethanol works as an oxygenate, helping the fuel burn more completely and causing fewer emissions.

GM has 11 2008 models that can run on E85.

Burning ethanol as a fuel reduces carbon dioxide emissions by 21 percent over gasoline and releases no particulate matter. However, burning ethanol creates more ozone, leading to smog and potentially more respiratory health problems. Studies on ethanol emissions are ongoing. Ethanol also has less energy density than gasoline, so a car running on E85 gets worse mileage than the same car running on E10.

Another downside to ethanol is that, because the fuel is made from corn and other food crops, heavy demand for ethanol drives up food prices. Because global food prices are rising, the trade-off is problematic. Current research into cellulosic ethanol made of grasses or even trash seems poised to help ease this controversy.

In the United States, Ford, GM, Chrysler, Mercedes-Benz, Mazda, and Nissan sell cars that can run on ethanol mixes up to E85. The National Ethanol Vehicle Coalition hosts a map on its Web site showing the locations of E85 stations around the country.
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