The primary environmental benefit of a CNG car is that it produces 90 percent fewer smog-forming pollutants ( oxides of nitrogen ) , compared to the output of a conventional gas engine , said Steve Ellis , manager of alternative fuels for American Honda Motor Co . Scientists need to determine which alternative fuel is best for future . Some say compressed natural gas could be the answer . Only only one CNG - powered vehicle remains on the US market today . About 1,600 CNG refueling stations in California , compared to 200,000 gas stations .
Scientists need to determine which alternative fuel is best for future . Some say compressed natural gas could be the answer . Only only one CNG - powered vehicle remains on the US market today . About 1,600 CNG refueling stations in California , compared to 200,000 gas stations .