Not later than 2 years after November 15, 1990, the Administrator shall promulgate regu- lations establishing a voluntary opt-in pro- gram under this subsection pursuant to which- (A) clean-fuel vehicles which are required to be produced, sold, and distributed in the State of California under this section, and (B) clean alternative fuels required to be produced and distributed under this section by fuel suppliers and made available in Cali- fornia may also be sold and used in other States which submit plan revisions under paragraph