A growing use for natural gas is as a transportation fuel. Compressed natural gas (CNG) is used in cars and trucks and liquefied natural gas (LNG) is used in over-the-road tractor-trailer trucks. According to the Green Car Journal, natural gas is a clean fuel that is almost exclusively domestically sourced and is typically priced 30% less than gasoline. It also fast fills in about five minutes at fueling stations that offer natural gas dispensers.

While a number of U.S. auto manufacturers have announced that they will be manufacturing CNG vehicles, the Honda Civic Natural Gas is the only CNG production car available in the United States. In fact, the Civic Natural Gas was just voted “the 2012 greenest car in America.” The car is the cleanest-running internal combustion vehicle certified by the U.S. Environmental Protection Agency, with a 48 MPGe (equivalent) highway fuel economy rating. Priced at $26,155, it's available at 200 Honda dealers in 36 states. 

The six-judge panel on the Green Car of the Year jury selected the Civic Natural Gas from a field of five contenders, including the Ford Focus Electric, Mitsubishi i electric vehicle, Toyota Prius V and Volkswagen Passat TDI. Jury members included Carl Pope, chairman of the Sierra Club; Frances Beinecke, president of the Natural Resources Defense Council; and Jean-Michel Cousteau, president of the Ocean Futures Society, among others.

“This year's Green Car of the Year finalists underscore that there is no single solution to our transportation challenges," said Ron Cogan, editor and publisher of the Green Car Journal, which issues the annual award. "Virtually every automotive manufacturer is exploring green technology in several forms."