Currently, Section 202 of the CAA authorizes the EPA
Administrator to establish “standards applicable to the
emission of any air pollutant from any class or classes of
new motor vehicles or new motor vehicle engines, which
in his judgment cause, or contribute to air pollution which
may reasonably be anticipated to endanger public health
or welfare.” 42 U.S.C. § 7521(a)(1). Any such regulation,
which currently applies to emissions of hydrocarbons,
carbon monoxide, oxides of nitrogen and particulate mat-
ter, may take effect only after any necessary period “to
permit the development and application of the requisite
technology, giving appropriate consideration to the cost of
compliance.” Id. § 7521(a)(2).
Section 209(a) of the CAA prohibits any state or political
subdivision from adopting or attempting to enforce “any
standard relating to the control of emissions from new
motor vehicles or new motor vehicle engines.” 42 U.S.C.
§ 7543(a). Section 209(b) requires EPA to waive federal
preemption for California, if California has determined
that its state standards “will be, in the aggregate, at least
as protective of public health and welfare as applicable
Federal standards,” unless EPA finds that California’s
determination is arbitrary and capricious, the state doesn’t
need the standards to meet compelling and extraordinary
conditions, or the standards are not consistent with §
7521(a). Id. § 7543(b). Section 177 allows a state to adopt
and enforce standards identical to California standards for
which a waiver has been granted, as long as the standards
are adopted at least two years before the commencement
of the model year to which they apply. Id. § 7507.
II. Environmental Policy and Conservation Act
ed “provid[ing] for improved energy efficiency of motor
vehicles.” Pub.L. No. 94-163, § 2, 89 Stat. 87, 874 (1975)
(codified at 42 U.S.C. § 6201). EPCA’s Title III amended
the Motor Vehicle Information and Cost Savings Act by
adding a new Title V, *306 devoted to improving automo-
Title V set mandatory average fuel economy performance
standards for passenger automobiles, beginning in model
year 1978 at eighteen miles per gallon (mpg) and increas-
ing to 27.5 mpg by model year 1985. This had the effect
of requiring manufacturers to improve the fuel economy
of their fleets by fifty percent by model year 1980, and by
one hundred percent by model year 1985. General Mo-
tors, 898 F.2d at 167. Although Congress set the standard
for passenger automobiles at 27.5 mpg by 1985, EPCA
authorizes the Secretary of Transportation to set standards
at the maximum feasible level for light duty highway ve-
hicles for each model year, and for passenger automobiles
after model year 1985. See S.Rep. No. 94-516, at 119,
153-54 (1975) (Conf.Rep.), reprinted in 1975
U.S.C.C.A.N.1956, 1959-60, 1994-95. The Secretary of
Transportation has delegated his EPCA authority to the
National Highway Traffic Safety Administration
(“NHTSA”). 49 C.F.R. § 1.50(f).
The statute thus provided for fleet-wide average fuel
economy standards that would apply to all passenger au-
tomobiles or light-duty trucks sold by a manufacturer in a
given year, known as “corporate average fuel economy,”
or “CAFE” standards. Pub.L. No. 94-163, Sec. 301, §
502, 89 Stat. at 902. Manufacturers that fail to comply
may be assessed civil penalties. Id. § 508.
In determining maximum feasible average fuel economy,
NHTSA was directed to consider: “(1) technological fea-
sibility; (2) economic practicability; (3) the effect of other
Federal motor vehicle standards on fuel economy; and (4)
the need of the Nation to conserve energy.” Id. § 502; see
also S.Rep. No. 94-516 at 154, 1975 U.S.C.C.A.N. at
1995. It did not prescribe the formula for determining
CAFE standards but “gave [NHTSA] broad guidelines
within which to exercise its discretion.” Competitive En–
As enacted, EPCA included a preemption clause, §
509(a), which provided that “[w]henever an average fuel
economy standard established under this part is in effect,