VERY viable, indeed. CNG is a great 'middle' technology. Just not in our cars.

Why not buy the new Civic GX? It's EPA legal, no worries with emission laws, etc.

In the US, it's illegal to convert any car over, even partially, to run on any other fuel type than it was intended for. I looked into this extensively. The only approved kits (again, this is US) are the carburated kits for older cars. There is no legal EFI conversion NOR any legal add-on in the US and probably in Canada. Not sure, though, how you guys deal with these things up north. I hope you find something but the european manufacturers won't sell to us (generally) and the guys who will are selling used tanks (the tank is the big cost...solenoids, valves, and programming are cheap) that aren't always safe.

Keep us posted (maybe under a pseudonym) if it works out for you! Better to start with a natural gas car from a fleet (dodge made a ton of trucks/vans and Honda has made a CNG civic for years now) and put the extra money you'd save into the PHILL system, so you can refuel at home overnight!