It is actually a bi-fuel for those that don't click the link. There is a small gasoline tank for 280 miles of extra range. The 500 miles of CNG range is much better than what Honda's CNG Civic had, but you'll need it getting to a CNG station. The fill time won't be as fast as gasoline. CNG is a much cleaner fuel, but the lack of infrastructure means it will likely remain a fuel for fleets only. Audi also has a pilot plant that takes this a step further to make a liquid hydrocarbon. They call it blue crude, and it can easily be refined for diesel, or burned straight in a power plant.
