Opinion ID: 392800
Heading Depth: 2
Heading Rank: 4

Heading: Light-Duty Trucks

Text: 88 As we have had occasion to observe, some light-duty trucks come within the heavy-duty vehicle category for which particulate emissions standards are authorized by section 202(a)(3)(A)(iii), while others remain in a residual category, neither heavy-duty vehicles nor light-duty vehicles, governed by section 202(a)(1). See note 3 supra. This distinction does not affect our analysis of the present challenges to the particulate standard for light-duty trucks, however, because petitioners' objections are too general to implicate the varying nuances of the separate statutory provisions. NRDC essentially repeats its claims against the light-duty vehicle standard, while GM's attack focuses on the adequacy of the support in the record. 89 The EPA originally proposed the same particulate standards for light-duty trucks and light-duty vehicles, for both 1981 and 1983, see 44 Fed.Reg. 6650 (1979). The agency subsequently explained this proposal as reflecting the frequent congruity between light-duty truck and light-duty vehicle emission control: 90 It has been established in previous EPA rulemakings that manufacturers usually apply passenger car emission control technologies to light-duty trucks in order to comply with similar standards, since the engine configurations and type of use are very similar. For instance, GM's diesel light-duty trucks utilize the same diesel engines that are used in the GM 4,500 pound light-duty vehicles. 91 45 Fed.Reg. 48,133, 48,138 (1980) (footnotes omitted). The meager relevant data submitted in comments on the proposed rulemaking, however, suggested that light-duty trucks emit substantially more particulates than do passenger vehicles. See Regulatory Analysis at 53-58, J.A. 532-37. 92 The EPA analyzed these data, and concluded that the higher inertia weight and aerodynamic drag of light-duty trucks would necessarily result in higher particulate levels. 45 Fed.Reg. 14,496, 14,497 (1980). The higher road load horsepower of the trucks also contributed to greater emission levels. See 45 Fed.Reg. 48,133, 48,138 (1980); Regulatory Analysis at 54-55, J.A. 533-34. Furthermore, the expected improvements in light-duty vehicle emissions due to downsizing of vehicles and their engines would not be equalled by light-duty trucks. Regulatory Analysis at 58, J.A. 537. Finally, the increasing stringency over the next decade of the oxides of nitrogen standard for light-duty trucks would exacerbate particulate emissions. 34 Id. at 57, J.A. 536. Taking into account all these factors, the EPA concluded that the particulate emissions from light-duty trucks, before aftertreatment, would be thirty percent greater than those from light-duty vehicles. Therefore, the appropriate particulate standard, after trap-oxidizer treatment, would be 0.26 gpm rather than 0.20 gpm. 45 Fed.Reg. 14,496, 14,497 (1980). 93 The EPA's adjustments to the particulate standard were based on actual industry data, not theoretical projections of the effect of the measured factors on particulate emissions. GM offers an alternative explanation of the empirical observations, claiming that truck exhaust flow is increased by the different operating conditions of truck-type service, and faults the EPA for not including GM's hypothesized factor in its analysis. GM presents no data suggesting that inclusion of this additional factor would have resulted in a different extrapolation from the current observed emissions, and presented none at the time of its petition to the agency for reconsideration, see GM Petition, J.A. 805-16. We perceive no justification in GM's conclusory allegations for condemning as unreasoned the EPA's attempt to determine the relevant differences between light-duty trucks and passenger vehicles. 94 GM also attacks as unduly speculative the agency's assumption that trap-oxidizer technology developed for light-duty vehicles can be applied to light-duty trucks with only minor adaptations. Again, GM offers no specific reason for believing that particulate emission control devices will be any less suitable for light-duty trucks than previous emission control devices have been. GM's own pessimistic speculations cannot be conclusively refuted until the trap-oxidizer is completed, but as we have stated before, the mere possibility that unforeseen complications will develop does not render a prediction unreasonable. 35 95 Finally, NRDC's challenge to the particulate standard for light-duty trucks is more candidly a variation on its objections to the light-duty vehicle standard. NRDC denies that a standard based on the worst performing diesel can accomplish the greatest degree of emission reduction achievable within the meaning of section 202(a)(3)(A)(iii). We have already upheld the worst-performing-diesel standard for light-duty vehicles as within the EPA's regulatory discretion, and we find that the similar standard for light-duty trucks is equally so.