"The RFS program requires major American refiners, blenders and importers to use a minimum volume of renewable fuel each year between 2007 and 2012. The minimum level or "standard" which is determined as a percentage of the total volume of fuel a company produces or imports will increase every year"

For 2007, 4.02%, roughly 4.7 billion gallons, will have to come from renewable sources. You can read all about it at www.greencarcongress.com