An amendment to conduct a study of the antitrust and tax implications and the impact on retail motor vehicle dealerships and consumer of the practice where manufacturers sell or lease, or offer to sell or lease, any passenger car, truck or station wagon to any person during any period of time at a price which is lower than the price at which the same model of passenger car, truck or station wagon, similarly equipped, is sold or leased, or offered for sale or lease, to such retail dealers during the same period. Report on this is required by the Secretary to the President and Congress within 12 months.