I saw this on youtube. A very useful invention - cars that run on compressed air. This is very good. Finally an alternative to petroleum products. Watch this.

[ame=http://m.youtube.com/watch?v=wtsAm3t2HDA]FREE ENERGY - Air Powered Vehicles - YouTube[/ame]

However, this project did nor push through because it is too expensive to compress air. Therefore, this project was abandoned.