The Clean Air Act Amendments of 1990 created two programs: winter oxygenated gasoline in some cities to reduce carbon monoxide emissions and reformulated gasoline (RFG). The winter oxygenated gasoline program began near the end of 1992, and the year-round RFG program began in January 1995.
RFG included an oxygenate requirement from 1995 until 2006. Congress replaced RFG’s oxygenate requirement with the Renewable Fuel Standard (RFS). The Energy Policy Act of 2005 created the RFS and deleted RFG’s oxygenate requirement. In 2006, EPA modified its regulations for RFG and deleted the oxygenate requirement. The RFS was expanded by the Energy Independence and Security Act of 2007. “RFS1” is often used to refer to the original RFS. “RFS2” refers to the revised RFS.
In addition, a few states require 10 volume percent ethanol in gasoline, including Minnesota, Missouri and Oregon. Florida has repealed its ethanol mandate. Hawaii currently has an ethanol mandate, but this will be removed at the end of 2015. Today, more than 90 percent of U.S. gasoline contains 10 volume percent ethanol.