Looking at that same Civic (there's a fleet of them here in Syracuse, NY) I actually drafted a white paper of sorts last year, intended to explore the issues/technology of CNG for presentation to the Club Racing department.

However, I set it aside when I fell out of favor with the PTBs re: the CRB, its relationship with the ITAC, and my subsequent resignation from the Ad Hoc committee. Frankly, I have every reason to believe that some individuals among the decision makers are likely to view anything that comes from me as poison. If anyone would like to lead the charge on this, I'll gladly send them what I have.

CNG is almost certainly a SAFER fuel than gasoline. It is lighter than air so any release dissipates naturally and quickly. There are DOT requirements on CNG fuel bottles that include resisting a gunshot, and the transportation industry views them as safe enough that they are used in public transport and school buses.

The only substantive downsides I identified were related to viability for endurance racing - limited mileage on a tank and a lack of any affordable technology to fill bottles quickly.

K