my son works for a natural gas company located in central and north AR,
last year they had a vehicle give away and gave their employees 30 new GM suv's or pickup's that had the NG option.
my son said one of the trucks would make the trip home (300 miles) on natural gas, then just flip a switch and go back on gas.
more and more vehicles are being converted, as in all new things, the more you do, the cheaper it gets. some over the road trucks are being converted as they stay on major interstates, the big fuel stations are adding NG all the time.
one thing to think about: we have lots of NG in the US, we do not have to buy and beg the fuel from people who wish us dead, but want our money more.
you really want to see NG sales pop, let some crazy's blow up a few old ships in arab country shipping lanes, stopping the flow of oil, we are at their mercy everday.