Natural gas powered cars...

IMO CNG will eventually be the replacement for gasoline for many of the reasons stated above. The US has about a 200 year supply with KNOWN reserves. The only drawback is that some of those reserves are in shale. The extraction process is pretty high on the pollution side. If they get it cleaned up, I think it'll be really viable in the long term.

Right now, infrastructure is really the only thing holding it back. It is a chicken or the egg scenario. There aren't a lot of stations because there aren't a lot of vehicles. I suspect subsidies will eventually change this but it will be a slow process...

BTW, in India, CNG is the norm. The majority of the taxis are fueled with CNG. Lots of passenger cars and trucks use it too. However you need to keep in mind that CNG will have a lower range. CNG has fewer BTUs than gasoline and of course there is that heavier fuel tank that you have to worry about.

I don't think CNG will be the silver bullet that ends the oil age but it will definitely be part of the answer. IMO electric cars will start to play a bigger roll in the next 20 years. Especially in major cities. If battery or capacitor technology ever catches up with consumer needs, it will become the really dominant power storage medium. CNG will then be regulated to powerplants to charge those batteries. (unless we really go nuke)