Japanese automaker Honda has expanded the dealership of its compressed natural gas-powered Honda Civic GX with the recent addition of Oklahoma as a sales base.

Oklahoma became the fourth state in the U.S. to sell the GX, which was launched in California in 2005. Since then, retail sales have expanded to New York in 2006 and Utah in 2009.

“Honda seeks market opportunities for the Civic GX where strong natural gas refueling infrastructure exists,” Elmer Hardy, senior manager at Honda’s alternative fuel division, said in a news release.

KTUL-TV reported that Oklahoma provides a tax credit of up to $2,500 for motorists who buy CNG equipment to fuel their vehicle at home. At the same time, consumers can also claim a 50 percent tax credit for CNG vehicles, such as the Civic GX.

The 2010 Civic GX boasts an EPA rating of 24 mpg city and 36 mpg highway and was named the “greenest vehicle” by the American Council for an Energy Efficient Economy. It is the only OEM-built, CNG-powered passenger car assembled in the U.S.