D issued Motor Vehicle Safety Standard No. 202, which requires that all new passenger cars manufactured for sale in this country must be factory-equipped with front seat head restraints which meet specific federal standards. Ps' grievance appears to flow not from the recognition and establishment of the head restraint as an essential safety device but from the adverse impact upon their business inherent in a vehicle standard which necessarily requires that the head restraints be factory installed. Ps filed suit and attack the Standard from the procedural standpoint raising a number of issues as to the manner in which the legislative grant of authority was exercised. Ps also contend that head restraints endanger, rather than promote, passenger safety. Ps claim that Ds misconceived their authority under the Act with respect to the kind of rulemaking proceeding they could hold. Ps contend that the rulemaking procedures provided by Section 4(b) (informal rulemaking) of the Administrative Procedure Act (APA) were not appropriate for the promulgation of this safety standard. They contend that the more stringent procedures of Sections 7 and 8 of the APA (formal rulemaking) are required. There is no dispute that D engaged in informal rulemaking. Ps do not dispute that there was the required notice, 'an opportunity to participate . . . through submission of written data, views, or argument,' and 'a concise general statement of [the rule's] basis and purpose' when it was issued. Ps' central claim is that the Standard is invalid because this manner of proceeding was unauthorized from the beginning since it did not comport with the requirements of Sections 7 and 8 of the APA.