We have talked about how newr vehicles are more fuel efficient and cleaner running than older vehicles. There are a lot of other choices out there in new cars. Electric and hybrid cars are fast becoming a favorable alternative to fuel powered cars. What we often forget to think about are the other alternatives without buying a new car. For example a diesel engine can be easily converted to run on biofuels (for example vegetable oil used by fast food retaurants). Often this is cheaper to run too. Fast food places have to pay to dispose of the oil, if they can give it to someone with a converted car there is no cost to them, they may evern sell it for a lower cost than traditional fuels. This site talks about other reasons to use biofuels. The USDA is currently working on the resources of biofuels and the uses for them.