((a)) ** .—** Except as provided in this section, a State or a political subdivision of a State may prescribe or enforce a bumper standard for a passenger motor vehicle or passenger motor vehicle equipment only if the standard is identical to a standard prescribed under .

((b)) ** .—** This chapter and chapter 301 of this title do not affect the authority of a State to enforce a bumper standard about an aspect of performance of a passenger motor vehicle or passenger motor vehicle equipment not covered by a standard prescribed under if the State bumper standard—

((1)) does not conflict with a standard prescribed under chapter 301 of this title; and

((2)) was in effect or prescribed by the State on .

((c)) ** .—** The United States Government, a State, or a political subdivision of a State may prescribe a bumper standard for a passenger motor vehicle or passenger motor vehicle equipment obtained for its own use that imposes additional or higher standards of performance than a standard prescribed under .