Some critics argue against subsidies for budget reasons - and they should. Other critics claim "fracking" will destroy American water supplies - that claim is disingenuous, because it blindly ignores the environmental harm of the incumbent fuel - gasoline.
Regarding the subsidy argument, ask your congressman why the US went into Iraq, twice. Why are we in Libya? What justification is there for these costs? I say that it's oil security. Why are these military costs not considered a "subsidy" for crude oil?
CNG works. As this blog shows, I've been driving a Honda Civic GX for 18 months and 28,000 miles in Oklahoma. Infrastructure? Most of it's already there - most gasoline stations have a natural gas meter connected to the store! All it takes is a compressor to get the natural gas from that existing meter into my car! No gasoline tankers twice a day, no refinery, no tank farm, no crude oil hauled from the Middle East.
Regarding "fracking", which sounds more environmentally risky? Crude oil and gasoline shipped around the world in a bunch of buckets or a complete closed system that flows pressurized fuel from 8,000 ft underground to the injectors in my car? Please consider that big picture when you are claiming that "fracking" is killing babies while you fuel your car with $3.40/gal gasoline.
Another question to consider - who benefits from the $1.39/gal paid for CNG fuel? Tracing back from the station - the American station owner and the American workers that built it, the American pipeline company and the American workers that built it, the American producer and the American driller who drilled the well, and finally, the American mineral owner who gets over 10% over the proceeds in royalty checks. If you follow the money on gasoline, you'll find yourself outside America real soon...