Every factory CNG car sold in the U.S. is out of production. The Honda Civic GX (1998 to 2011) and Civic Natural Gas (2012 to 2015) were the only dedicated natural gas cars sold to the public in volume; GM sold a bi-fuel Impala for 2015 and 2016. All of them are used cars now, and the single most important thing to check on any of them is the date and inspection history of the CNG cylinder.
Honda Civic GX and Civic Natural Gas
| Model years | 1998 to 2011 as Civic GX; 2012 to 2015 as Civic Natural Gas |
| Engine | 1.8 L four-cylinder (2006 on), dedicated CNG, about 110 hp |
| Tank | About 8 GGE at 3,600 psi, in the trunk (trunk space roughly halves) |
| Range | Roughly 200 to 250 miles; EPA rated the 2012 to 2015 car at 27 city / 38 highway mpg-equivalent |
| Emissions | Certified as an advanced technology partial zero-emission vehicle in California; qualified for solo HOV-lane access there for years |
| What to check used | Cylinder label date, 3-year inspection stickers, fuel-line and regulator condition, and whether a public station is within your daily radius |
The car drives like any other Civic of its year, a little slower on the highway because the engine gives up some power to run on gas. Owners liked the fuel cost and the HOV sticker, and disliked the trunk and the range. Between 2011 and 2014 Honda offered them with a Phill home compressor promotion; the Phill unit is no longer supported, and home fueling today means a used unit and a willingness to maintain it.
Bi-fuel sedans and other cars
- Chevrolet Impala bi-fuel (2015 to 2016). A 3.6 L V6 with a 7.8 GGE CNG tank in the trunk and the standard gasoline tank; about 150 miles on CNG before switching seamlessly to gasoline. Sold mainly to fleets; a few thousand exist.
- Ford Crown Victoria and Lincoln Town Car CNG (1990s to 2000s). Dedicated natural gas taxi and fleet cars, now rare and mostly retired.
- Conversions. Any gasoline car can in principle be converted with an EPA- or CARB-certified bi-fuel kit; the conversion page covers cost and rules. In practice conversions cluster on pickups, vans and taxis, where the payback is faster.
Buying a used CNG car: the checklist
- Read the cylinder label. It gives a manufacture date and a do-not-use-after date (15, 20 or 25 years). A 2005 Civic GX with a 15-year tank expired in 2020. Stations are not supposed to fill an expired cylinder, and a new one installed runs into the thousands.
- Ask for inspection records. Federal rules require a visual inspection of the cylinder and mounting every 3 years or 36,000 miles by a qualified inspector. No records means you inspect before you buy.
- Look at the range circle. Put your home and workplace into the map. If there is one station and it is a fleet yard with limited hours, the car will sit.
- Price the fill. The price guide shows what CNG costs per GGE; at 8 GGE a fill is cheap, but the savings only add up if you actually drive it.
- Check the pressure. Some older fleet stations are 3,000 psi. Your 3,600 psi tank will fill to about 80 percent there, which trims the range further.
Looking for a pickup instead?
The bi-fuel F-150, Silverado 2500HD and Ram 2500 are covered under CNG trucks, since they share the station and range considerations of the heavy-duty side more than the Civic's.
FAQ
What years was the Honda Civic GX sold?
Honda sold the Civic GX from the 1998 through 2011 model years and renamed it Civic Natural Gas for 2012 through 2015. Early cars were fleet-only; retail sales in California began in 2005 and expanded to a few dozen states before the model was dropped.
How much does it cost to fill a Civic GX?
The tank holds about 8 gasoline gallon equivalents, so at a typical CNG price of roughly $2.50 to $3.50 per GGE a fill costs about $20 to $28 and buys 200 to 250 miles.
Can a Civic GX use a 3,000 psi station?
Yes, but it will only fill to about 80 percent. The GX tank is rated for 3,600 psi. Most public stations dispense 3,600 psi; the station badges on this site show which pressures each offers.
What is the CNG tank expiration date?
Every CNG cylinder carries a do-not-use-after date on its label, set by the manufacturer at 15, 20 or 25 years from production. Stations are not supposed to fill an expired tank, and a replacement cylinder for a Civic GX costs several thousand dollars installed.