Maybe you have or not have heard of the upcoming TATA Air Car
This car is suppose to use compressed air for Fuel.
The video explains how it works.
A friend of mine who I was telling this to said, that this may create problem in the long run for the environment because we will be compressing a lot of air if this becomes a mass product.
He said that it will effect the entire air structure of earth if we compress too much air.
DO YOU know more about this, as I know I do not know much more about this, if you do, do let me know.
Introduction to the TATA Air Car http://www.youtube.com/watch?v=D-A3XHFT5qc