Regulation of Fuels and Fuel Additives: Revised Definition of Substantially Similar Rule for Alaska

EPA is taking direct final action to revise an interpretive rule defining the term "substantially similar" for unleaded gasoline as that phrase is used in section 211(f) of the Clean Air Act (the Act). To meet the current definition, fuel or fuel additives must possess, at the time of manufacture, all of the physical and chemical characteristics of an unleaded gasoline as specified in ASTM Standard D 4814-88 for at least one of the Seasonal and Geographical Volatility Classes specified in the standard. EPA is amending the definition to allow some additional flexibility for the vapor/liquid ratio specification for fuel introduced into commerce in the state of Alaska in order to improve cold starting for vehicles during the winter months in Alaska.