States will no longer have to add ethanol or MTBE to gasoline as a means of controlling emissions; a move experts say will save up to eight cents per gallon, according to new rules just released by EPA. The new rules eliminate a requirement of the 1990 Clean Air Act (CAA) requiring gasoline used in urban heavy smog areas to contain at least 2% oxygen by weight. Most states used ethanol or MTBE to meet the oxygenate requirement.