In 2012 the only United States factory manufactured CNG passenger car sold to retail customers was the Honda Civic Natural Gas (formerly known as Honda Civic GX). The 8 gallon CNG tank provides a range of about 250 miles (402 km). With near-zero emissions, the EPA identifies it as the cleanest internal combustion vehicle commercially available on earth. It is also one of the least expensive alternative vehicles in the near-zero emissions range. Advanced vehicle technology tax credits could make it even more affordable. You can identify a CNG vehicle by its logo. CNG conversion systems are offered on some vehicles.