Publicized recently by Texas billionaire T. Boone Pickens as an answer to America's "oil addiction," NGVs have actually been around since the 1930s.
Today there is about one NGV for every 1,000 cars on the road. The vehicles can either be dedicated NGVs, which run only on natural gas, or bi-fuel vehicles, which can run on either natural gas or gasoline often switching at the push of a button.
Natural gas itself is a methane rich fossil fuel often found above and below petroleum reserves. Like gasoline, natural gas is combustible and can, therefore, be used to power an internal combustion engine.
Advantages of NGVs
Natural gas prices are less volatile than gasoline prices, offering financial certainty that some car buyers find attractive.
The price of natural gas is comparable to gasoline, and a mature infrastructure exists to move the fuel across the country. While some associate natural gas with fire, it's possible that a NGV is actually safer than a gasoline vehicle due to a shell protecting the fuel storage cylinders and the fuel's properties.
Another big advantage of natural gas is that it's a relatively clean burning fuel. This means less vehicle maintenance, as well as fewer emissions. Burning natural gas leads to higher carbon monoxide emissions than oil, but otherwise the fuel is cleaner than other fossil fuels.
Source: EIA - Natural Gas Issues and Trends 1998
NGVs do have some drawbacks. They retail for between $4,000 and $8,000 more than a comparable gasoline model, while converting a traditional gasoline model will cost you around $3,000 to $5,000.
The vehicles are also less spacious than traditional gasoline vehicles due to their fuel storage cylinders, and another inconvenience is that they do not have room for a spare tire in the trunk. A NGV's range is limited by storage capacity, they will only get about 200 miles between fill-ups.
Fuelling is not as easy as gasoline, but still relatively simple. Approximately 1,300 NGV fuelling stations exist in the US.
A Honda Civic GX, Honda's NGV model, actually comes with its own personal natural gas pump, which can be attached to your home's existing natural gas pipes for about $500 to $1,500. This personal pump is the slow-fill variety, however, and will take between five and eight hours to refill.
At a natural gas fuelling station you'll have access to a fast-fill system that replenishes your car in about the same amount of time as gasoline.