Now that is utilizing your resources at it's finest! However, I don't think you will be seeing anything like that in the US any time soon! I guess it would make a good excuse for an extra large t-top...
Seriously though, I have often wondered why cng was not more widely used as a vehicle fuel. It is readily available from wells throughout North America, there is a reliable system to transport CNG from the wells all the way to the resellers. It is (or at least was with carbs) easy to convert a vehicle to use CNG. And it is lighter than air so you don't have the issues that you can have with propane. I guess the downside is the high pressures needed for storage, the high volumes needed, and the lower btu content.
The whole alternative fuel issue is moot until consumers decide what they want to buy. Right now, consumers want to buy gasoline and diesel so that is what is being supplied. When enough demand for an alternative fuel develops, then someone will decide they can make money selling it and provide it (whatever "it" happens to be). That is basically why the hybrid cars have taken off. And remember that alternative fuels have been around since before they were alternative ( http://www.stanleysteamers.com/
), it just happens that gasoline and diesel were cheap and easy so they became popular.