The Maxximus LNG 2000, a $1 million supercar built in Indianapolis by entrepreneur Marlon Kirby, has a top speed of 200 mph and runs on natural gas, either compressed or liquid. The car is equipped with an all-aluminum V-8 engine that cranks out 1,600 hp. The designer decided to take advantage of the fact that the U.S. currently has an estimated 100-year supply of natural gas, thanks to hydraulic fracturing, a new method of extracting natural gas trapped in shale rock. Although natural gas is mainly used to generate electricity and by industrial firms, there are about 120,000 natural-gas-powered vehicles on the road, and only 900 filling stations can fuel them up. But with drivers paying only the equivalent of $2 per gallon for natural gas, this could change, especially if petroleum fuel goes up in price.