One of the largest market obstacles for natural gas vehicles has been the lack of an extensive retail fuel infrastructure. Gasoline stations are ubiquitous, but it's hard to find somewhere to refuel a natual gas car.
Even electric vehicles are more practical -- as you can plug those in at home. As a result, this has meant that the natural gas has only been a cost-effective fuel choice for centralized fleets with their owen refuelilng stations, such as buses, delivery trucks, and utility vehicles.
That may begin to change, however. Honda is announcing that it will begin selling home refueling units for natural gas vehicles, and expects to market the device in California and a few other states. It will be interesting to see whether this development increases consumer acceptance of natural gas vehicles.