I believe that natural gas vehicles are practical if we start producing more of them on a wide scale basis. They can help keep our environment clean through a simple fueling process. I think that in order for them to become more practical than they already are, we need to enable a wide spread production of them.
Tanks for a liquefied gas vehicle will probably weigh more, but the compression tanks can take up less space in a vehicle than a standard diesel/unleaded gas tank if placed properly The risk of fire is less because the compression tanks won't explode as readily. Ironically, Asia leads the world in use of LGVs. There is no reason why the United States can't follow--natural gas is already a prominent heating fuel in many urban areas. Natural gas lines can run to fueling stations already in operation, so any excuse for not developing the necessary infrastructure is bogus. The necessary investment to run natural gas vehicles will pay for itself in time--American automakers simply don't want to invest the time and money to do it because they make money with the status quo already.