Whereas regular gasoline costs around $3.20 per gallon, the CNG America station on 900 S is at $1.66 per gallon equivalent. While one can convert their own car to run on natural gas (apparently for $12-18k, although Utah will give you a tax credit up to 50% of that), the Honda Civic dedicated CNG model has been in production since 1998 and "remains the only dedicated production sedan to run solely on compressed natural gas."
While the regular Honda Civic costs $18,390 the CNG version runs $24,140 (after Utah's $2,500 tax credit), which is a difference of $5,750. Since the gas mileage for both cars (considering the CNG's gasoline gallon equivalent) is roughly the same and the price of CNG is half as much as gasoline, driving 12,000 miles a year (at 38 mpg) would make the CNG cost effective after.... ~11 years. Hmm, not too bad, especially since CNG engines are known to last much longer than those of regular vehicles because of how efficiently they run. (I have known some enthusiastic CNG owners that buy their cars used, from public fleets and such, which appears another great way to do it.)
CNG vehicles also let you fill up in the comfort of your own home, help reduce our dependence on foreign oil, and have the following (substantial) environmental benefits:
Natural gas vehicles generally emit 13–21 percent fewer GHG emissions than comparable gasoline and diesel vehicles on a well-to-wheels basis.
Medium and heavy duty natural gas engines were the first engines to satisfy U.S. Environmental Protection Agency's (EPA) demanding 2010 emission standards for nitrogen oxides (NOx).
The light-duty Honda Civic Natural Gas held the American Council for An Energy-Efficient Economy’s (ACEEE) title of “Greenest Vehicle” for eight consecutive years.
Natural gas primarily consists of methane (around 90 percent), with small amounts of ethane, propane, and other gases. Methane is lighter than air and burns almost completely, creating carbon dioxide and water as byproducts.