Obama's Auto History -- Fuel Efficiency in Cars and Carbon Emissions- WSJ.com

You may have to get to the end of this article to see where it is going, but basically, it makes the point that car efficiency CAFE standards set by the government don't result in savings of oil or carbon emissions. The one thing that can be expected to reliably reduce both is to place a meaningful carbon tax on oil, that keeps the price of oil high enough to both dissuade usage as well as providing a price floor that encourages competitive alternate fuel technologies to compete with oil. As long as developers of alternate fuels know that the King of Saudi Arabia can make them uncompetitive by conspiring with his buddies to lower fuel prices for a year, it will be difficult to make real progress. The punch line is that neither political party wants to be responsible for the politically unpopular act of enacting such a tax, including the media-be sainted Obama.
Obama's Auto History - WSJ.com