we've basically peaked in oil extraction and its entirely likely we will see a decline sometime in the next decade. So I think the car usage is going to make an impact on itself. I also agree that there is no way we are going to be able to replace all the cars with biodiesel. hydrogen is just a sad joke. The thing that you need to do is think about how you can help create a more viable public transport and a local based economy. Think about where you get your food, your electricity and just about every thing else you own.