(3) (A) To the extent practicable, the Secretary shall acquire both dedicated and dual fueled vehicles, and shall ensure that each type of alternative fueled vehicle is used by the Federal Government. (B) Vehicles acquired under this section shall be acquired from original equipment manufacturers. If such vehicles are not available from original equipment manufacturers, vehicles converted to use alternative fuels may be acquired if, after conversion, the original equipment manufacturer’s warranty continues to apply to such vehicles, pursuant to an agreement between the original equipment manufacturer and the person performing the conversion. This subparagraph shall not apply to vehicles acquired by the United States Postal Service pursuant to a contract entered into by the United States Postal Service before October 24, 1992 , and which terminates on or before December 31, 1997 . (C) Alternative fueled vehicles, other than those described in subparagraph (B), may be acquired solely for the purposes of studies under subsection (b), whether or not original equipment manufacturer warranties still apply. (D) In deciding which types of alternative fueled vehicles to acquire in implementing this part, the Secretary shall consider as a factor— (i) which types of vehicles yield the greatest reduction in pollutants emitted per dollar spent; and (ii) the source of the fuel to supply the vehicles, giving preference to vehicles that operate on alternative fuels derived from domestic sources. (E) (i) Dual fueled vehicles acquired pursuant to this section shall be operated on alternative fuels unless the Secretary determines that an agency qualifies for a waiver of such requirement for vehicles operated by the agency in a particular geographic area in which— (I) the alternative fuel otherwise required to be used in the vehicle is not reasonably available to retail purchasers of the fuel, as certified to the Secretary by the head of the agency; or (II) the cost of the alternative fuel otherwise required to be used in the vehicle is unreasonably more expensive compared to gasoline, as certified to the Secretary by the head of the agency. (ii) The Secretary shall monitor compliance with this subparagraph by all such fleets and shall report annually to Congress on the extent to which the requirements of this subparagraph are being achieved. The report shall include information on annual reductions achieved from the use of petroleum-based fuels and the problems, if any, encountered in acquiring alternative fuels. (F) At least 50 percent of the alternative fuels used in vehicles acquired pursuant to this section shall be derived from domestic feedstocks, except to the extent inconsistent with the multilateral trade agreements (as defined in section 3501(4) of title 19 ). The Secretary shall issue regulations to implement this requirement. For purposes of this subparagraph, the term “domestic” has the meaning given such term in section 13211(7) of this title . (G) Except to the extent inconsistent with the multilateral trade agreements (as defined in section 3501(4) of title 19 ), vehicles acquired under this section shall be motor vehicles manufactured in the United States or Canada.