Natural gas is great if you're a commuter driving everyday. It's a dual fuel system. Gasoline and natural gas. A flick of the switch and you can't tell the change over. I kept about a quarter tank of gasoline all the time and once in a while ran it on that to keep the injectors active. Fuel injector cleaner was needed more often too. Natural gas has it's drawbacks as KillerKnight just said. The tanks are very heavy and, in a car, needs heavy duty springs.
I had a Crown Vic on natural/gasoline and drove it 60000 miles. It's an expensive conversion but in my case there were grants available that helped the initial cost by a large amount. I was able to get a payback in 3 months. A round trip of 120 miles provided a saving of over 50%. There was a fuel station at either end of my trip so it was convenient for my purpose. When I moved from Ontario to Manitoba there weren't any fueling stations available so--no more natural gas.
There was a noticeable power loss on natural gas as well, but for highway cruising it was just fine.
Geo.
