We've had our Civic GX for over 2 years and there are a few others on here who also have or have had Civic GXs.
-Fueling infrastructure can be dodgy, I've pulled up to CNG stations that were not functioning properly for a variety of reasons - the most common being that the credit card reader is down. There's rarely ever an attendant on duty so if it doesn't work you can call the fueling company and hope for the best - but repairs can be a day away. The other big problem is that some stations will not give you a full tank because their equipment isn't capable of compressing the gas all the way up to the 3600PSI the Civic can store and some stations only have older 3000PSI filling equipment or the 3000PSI pump is the only one operable.
-Don't bother with home refueling. It's a headache. You need the natural gas plumbed to the station in your garage as well as upgraded 240V electrical wiring. Then you can count on a refueling experience of 4-12 hours. The home refueling devices also have a limited run time and must be refurbished at 6,000 hours. There's more discussion on that here on CNG Chat
. After a lot of research we decided to forgo purchasing a home refueling appliance.
-Service and maintenance are costly and must be done by specific CNG certified Honda dealers. Regular car stuff can be done at any dealer or by yourself (my girlfriend does the oil changes and stuff) but the CNG specific stuff must go to Honda, and that can be every other service. For us that means a 50 mile drive to Palmdale to the competent and reasonably priced Robertson Palmdale Honda. Also, the CNG cylinder is only certified for 15 years so after 15 years by law it MUST be replaced.
-Performance and acceleration are not even comparable with the Leaf. The Civic GX is slower than the regular petrol Civic.
-CNG cost can fluctuate/rise with petrol cost, though there is some protection from that when you have home refueling (but not always worth it as described above). For us, operating costs for the Civic GX are not too different from operating costs of the Prius.
-We bought our Civic GX used so I'm not up to date on the current subsidy status, but I'm pretty sure the subsidy for a CNG car is not as large as the $7500 subsidy for a Leaf from the federal government.
-Aside from a smaller trunk and different performance it's pretty much a regular Civic so expect everything you'd get with buying a Civic.
-Higher range than Leaf and where there is already fueling infrastructure refuels are only a 5-minute affair. There is no Level 1, 2, or 3 to worry about. If you're not using a home refueling device, and the fueling station is up and running properly, you'll get a fast refill. What you might not get is a completely full refill.
-In California at least you get carpool stickers just like the Leaf.
-As an alternative to petrol it makes a lot of sense if the fueling infrastructure is present in your region. Honestly we'd keep our Civic and sell the Prius if it weren't for the fact that Civic GX resale values are very good right now, our Prius is a newer car and still under warranty, and it makes more sense for us to keep at least one vehicle that's capable of a road trip to Vancouver and back.
I do like the Civic GX and the concept of CNG, particularly when compared to regular petrol-fueled vehicles, but when you compare it to the amenities and convenience of EVs I don't think it holds up as well. A Civic GX isn't a bad choice of vehicle by any means and if there were no plug in vehicles available today I'd likely have bought another new Civic GX.