dissenting:
The panel’s decision today invalidates an interpretative rule of the EPA that finds no *117contradiction, and indeed much support, in the language, purpose, and legislative history of the Clean Air Act Amendments of 1970. In so doing, it oversteps appropriate bounds for judicial interference with reasonable statutory interpretation by an enforcement agency. Disturbingly, it permits automobile manufacturers to circumvent in large part or even altogether section 207’s recall and repair obligations through a strategy of engaging in prolonged litigation.
To repeat a frequent incantation of this court, “[i]t is the settled rule that the practical interpretation of an ambiguous or doubtful statute that has been acted upon by officials charged with its administration will not be disturbed except for weighty reasons.” Chrysler Corp. v. EPA, 631 F.2d 865, 884 (D.C.Cir.) (quoting Brewster v. Gage, 280 U.S. 327, 336, 50 S.Ct. 115, 117, 74 L.Ed. 457 (1930)), cert. denied, 449 U.S. 1021, 101 S.Ct. 589, 66 L.Ed.2d 483 (1980). The majority opinion itself refers to the statutory language of section 207 as “ambiguous,” and the EPA’s interpretation in this case is an eminently “practical” one. Indeed, this court recently reviewed an EPA interpretation of the section 207 recall authority and observed that “[although this court has the duty ... to ‘decide all relevant questions of law,’ we recognize that the special expertise of the EPA in interpreting the legislation which it is called upon to administer requires that we defer to the judgment of the Agency when that judgment is reasonable and is consistent with the language and purpose of the legislation.” Id. (quoting the Administrative Procedure Act, 5 U.S.C. § 706). Therefore, in the absence of contradictory statutory language or a reasonably clear “contrary indication in the legislative history,” Whirlpool Corp. v. Marshall, 445 U.S. 1, 13, 100 S.Ct. 883, 891, 63 L.Ed.2d 154 (1980), an interpretative rule that “on its face appears to further the overriding purpose of the Act, and rationally to complement its remedial scheme,” id., must be upheld.1 I can find no legitimate reason for avoiding that mandate here.
The Panel By Its Own Admission Effectively Guts Section 207
The Clean Air Act’s unequivocal purpose is “to protect and enhance the quality of the Nation’s air resources so as to promote the public health and welfare and the productive capacity of its population.” 42 U.S.C. § 7401(b)(1). The EPA rule struck down by the majority obviously effectuates this purpose. When the EPA discovers a defect in a class of cars that results in excessive pollution during their useful lives, the rule assures that the manufacturer must fashion a remedy to fit the violation: the remedial plan must include “all properly used and maintained nonconforming vehicles in the subject class regardless of their age or mileage at the time of repair.” 45 Fed.Reg. 36,396, 36,397 (May 30, 1980).
This interpretation makes good practical sense because whatever their age at the time of the actual recall, nonconforming cars have been riding the roads for years in violation of pollution standards. Cars that are nonconforming during their useful lives do not cease to be a pollution hazard thereafter; in fact, it is sensible to presume that they are more likely afterward to be a hazard than conforming cars. To the degree they can be altered to decrease their pollution potential even after their useful lives, the public is benefitted. By the same *118token, to the degree they elude correction both during and after their useful lives, the public is cheated.2
Indeed, the majority candidly admits that its invalidation of the rule may “render[] useless” the EPA recall system. Maj.Op. at 997. In the majority’s words, “only an unusually uninventive lawyer will be unable in the context of today’s backlogged court dockets to prolong administrative and judicial appeals for at least several years,” with the result that “all or most vehicles involved in a recall” will be exempted from the repair obligation.3 Id. Certainly, a statutory construction which acknowledgedly produces such a bizarre result should be viewed with great skepticism. Only recently we stressed, “[w]e cannot interpret section 207 ‘in a manner which runs counter to the broad goals which Congress intended it to effectuate.’ ” Chrysler Corp. v. EPA, 631 F.2d at 888 (quoting FTC v. Fred Meyer, Inc., 390 U.S. 341, 349, 88 S.Ct. 904, 908, 19 L.Ed.2d 1222 (1968)). The panel has done so here.4
The Panel Opinion Is Not Consistent With The Language, History, or Past Interpretation of Section 207
The language of section 207 offers no firm ground for invalidating the EPA interpretative rule. The statute requires manufacturers to submit remedial plans for “vehicles or engines with respect to which .. . notification is given,” and directs the EPA Administrator to give such notification regarding a “class or category of vehicles or engines,” a substantial number of which exhibited nonconformity during their useful lives. 42 U.S.C. § 7541(c)(1). Thus, EPA reasonably interpreted the statute to require the manufacturers to include a car in their remedial plans if (1) a substantial number of cars exhibit nonconformity during their useful lives, and (2) the car is a member of that class. In this case, an estimated 68% of the automobiles in the class were exceeding emission standards during their lifetimes.
EPA’s class-based interpretation of section 207 enjoys precedential support. This court, in one of the few judicial cases to construe the recall provision, observed that “[ujnlike the discovery and cure of nonconformity of individual vehicles under the warranty provisions, the remedy at this stage is recall of the entire class of vehicles in order to correct the design, material, or workmanship defect .. .. ” Chrysler Corp. v. EPA, 631 F.2d at 868 (emphasis in original). Moreover, the remedial plans approved by EPA in the past have uniformly *119extended to all vehicles or engines in the recall class.5
The legislative history similarly supports EPA’s interpretative rule. The Report of the Senate Public Works Committee — upon which the majority heavily relies — refers to the recall of an entire “model or class” of vehicles or engines. S.Rep. No. 1196, 91st *120Cong., 2d Sess. 29 (1970). The Senate Committee bill designed two methods for EPA to assure in-use compliance with emission standards. First, after the development of a “quick test” method, the EPA could test the continuing compliance of “individual vehicles on the road.” Id. Alternatively, the EPA could conduct more intensive examinations of “representative sample[s] of a model or class,” and, after a finding of classwide noncompliance, EPA “could require the manufacturer to recall that model or class .... ” Id.; see id. at 111 (language of S. 4358 § 207) (If EPA finds that “statistically representative samples of any class or category of vehicles or vehicle engines ... do not conform,” then all “vehicle engines included within the class or category” should be notified); id. at 62-63 (section-by-section analysis) after the EPA “discovers defects through testing” of a class of vehicles or engines, it “shall order the manufacturer to notify ... purchasers of the defecti”) (emphasis added).6
Furthermore, when Congress revisited section 207(c) in 1977, the discussion assumed that the recall provision extended to all member vehicles or engines of the nonconforming classes. See, e.g., H.Rep. No. 294, 95th Cong., 1st Sess. 497 (“if a substantial number of systems fail during their on-the-road operation, the EPA can recall the entire lot for repair at the manufacturer’s expense”); id. at 498 (noting the possibility of “a recall of all of that model vehicle or engine type”); 6 Environmental Policy Division of the' Congressional Research Service of the Library of Congress for the Comm, on Environment and Public Works, 95th Cong., 2d Sess. 4540 (1978) (preliminary statement of Sen. Bentsen) (“section 207(c) authorizes the Agency to require the automaker to recall a given model run for needed repairs if the Agency determines that a substantial number of that model or engine type do not conform to the standards when in actual use”) (emphasis added); id. at 1220 (preliminary statement of Sen. Riegle) (“If a substantial number of systems fail during their on-the-road operation, the EPA can recall the entire lot for repair at the manufacturer’s expense”). Given these indicia of the congressional understanding of section 207(e), and the contemporaneous administrative policy (as evidenced by manufacturers’ remedial plans, see supra at 1002), it is reasonable to assume that Congress reaffirmed the EPA’s understanding of its recall authority when it revisited and ratified the recall provision in 1977. There is not a shred of evidence to the contrary.
The majority, nonetheless, believes it has found a stunning piece of legislative history that “la[ys] to rest” any doubt that the Congress intended to exclude from the recall remedy cars that “have exceeded the 50,000-mile limitation when presented for repair . ... ” Maj.Op. at 992-993. The full passage reads:
The Committee also recognizes the difficulty in any recall provision of notifying the owners of vehicles. The burden would be placed on the manufacturer to notify both the initial and subsequent purchasers of vehicles. The Committee expects that the manufacturer would not only depend on the files of the franchise dealer, but would, to the extent practicable, use State motor vehicle department registration files to obtain the names and addresses of subsequent purchasers of cars. By establishing a 50,000 mile, no year lifetime for the purpose of warranty, the Committee did not intend to relieve the automobile manufacturers of their responsibility to notify owners of older cars. The 50,000-mile period can be assumed to be 4 to 5 years and the manufacturer should be expected to notify any owner of a vehicle that is five years old *121or less as to failure to continue to perform to the standard. A decision not to require the manufacturer to repair the vehicle could be made after notice and after finding that the vehicle had exceeded the 50,000-mile warranty period.
S.Rep. No. 1196, supra, at 31. As the majority notes, the report deals with an earlier and different version of section 207 from the one ultimately enacted. The pertinent section of the Senate bill then being considered by the Committee defined “useful life” solely in terms of the 50,000 mileage limit (unlike the final act, it imposed no five year limit). Maj.Op. at 992; see S.Rep. No. 1196, supra, at 110 (section 207(c) of S. 4358). The majority overlooks, however, another much more significant difference between the Senate bill and the final enactment.
The Senate bill did not provide for any recall repair to correct noncompliance with emission standards; it provided only for the warranty repair obligation. Section 207(d)(2) of the bill merely directed the EPA to “order the manufacturer to provide prompt notification ... [to] purchasers of all ... vehicles or vehicle engines included in the class or category” that the EPA, through testing of “statistically representative samples,” had found to be out of compliance with the emission standards. S.Rep. No. 1196, supra, at 111. Once the purchaser received such a notice, he could have sought repair at the manufacturer’s expense under the warranty that was mandated by section 207(c) of the bill. See id. at 110. In the final enactment, by contrast, the recall provision includes an independent remedial obligation: a class of cars, discovered by EPA testing to be out of compliance, must “be remedied at the expense of the manufacturer.” 42 U.S.C. § 7541(c)(1). This obligation arises out of the manufacturer’s separate duty in a recall to formulate and follow an adequate remedial plan. Id. This obligation does not arise out of the warranty requirements, under which a manufacturer must guarantee the design and performance of the emission control systems. See id. § 7541(a)(1).
The passage from the Senate Report, relied upon so heavily by the panel, must therefore be read in conjunction with the more limited recall provisions in the bill then under consideration. In that context, the passage deals primarily with the difficulty placed on the manufacturers by section 207(d) of the bill — the “recall” section that requires manufacturers merely to notify purchasers of a class of vehicles or engines. As to that notice, the report says only that “[b]y establishing a 50,000 mile, no year lifetime for the purpose of warranty, the Committee did not intend to relieve the automobile manufacturers of their responsibility to notify owners of older cars.” S.Rep. No. 1196, supra, at 31. The meaning of this delphic sentence may never be entirely clear, but a reasonable interpretation is this. The 50,000 mile lifetime provision, of course, was found in the warranty section of the bill. See id. at 110 (section 207(c) of S. 4358). The sentence, therefore, was intended to make clear that “recall” notices, to the greatest extent practicable, should be sent to all owners of vehicles or engines in the test class that might conceivably have been eligible for repair under the warranty provision. The final sentence in the passage made clear that the “recall” notice did not automatically entitle its bearer to repair at the manufacturer’s expense. Because the warranty obligation ended when the vehicle exceeded 50,000 miles, the manufacturer would not have been required to repair a car that had exceeded the warranty mileage, even though it was a member of the “recall” class.
At the same time, the Committee recognized that the notice requirement could have created practical difficulties for manufacturers in locating the buyers of older cars, which might have traded hands numerous times.7 The Committee Report accordingly suggests that manufacturers con-*122suit “[sjtate motor vehicle department registration files” as well as their own “files of franchise dealer[sj” in order to “obtain the names and addresses of subsequent purchasers of cars.” Moreover, because under the Senate bill the “recall” notice functioned merely to alert consumers that they could assert their warranty rights against the manufacturer, such notice served no purpose if the consumer owned a car that had exceeded its useful life. In such cases, the warranty repair obligation — the consumer’s sole recourse under the bill — ended once the car travelled 50,000 miles. The Committee, apparently in acknowledgment of the practical difficulty of providing notice to owners of older cars, and in recognition of the pointlessness of requiring notice to owners of cars that had in all likelihood passed their useful lives, stated that “[tjhe 50,000-mile period can be assumed to be 4 to 5 years and the manufacturer should be expected to notify any owner of a vehicle that is five years old or less . ... ” This sentence is, of course, irrelevant to the statute as enacted, because Congress later added both the five-year age limit to the definition of “useful life” and added a recall repair obligation independent of the warranty terms.
Indeed, the fundamental thing about the passage from the Senate Report is its total irrelevancy to the present Act. For the law as enacted, in contrast to the Senate bill,8 imposes an independent recall repair obligation in addition to the warranty obligation. Section 7541 of Title 42 requires the manufacturer of a recalled class to submit and comply with a remedial plan for that class. Unlike the warranty repair obligation, the recall repair obligation extends to all member vehicles or engines in the recall class, and is not limited by the age of the vehicle or engine at the time of repair. Thus, the passage explains an earlier version of section 207 that limited the manufacturer’s repair responsibilities to those arising out of a warranty covering cars within their useful lives at the time of repair. It is simply inapplicable to the final version of the Act.9 The majority’s decisive reliance10 on the *123passage from the Senate Report is therefore misplaced.
In sum, then, I find nothing in the language, history, or purpose of the Act that readily supports the majority’s invalidation of the EPA’s interpretative rule. I believe it is an eminently reasonable rule, geared to fit the words and the theme of the Clean Air Act Amendments.
The Panel and the Concurring Opinions Are Inconsistent Internally As Well As With Each Other and Pose More Practical Difficulties Than the Rule That They Strike Down
Finally, I do not believe the panel opinion can logically coexist with its own proposed “legislative” rule or with Judge Wilkey’s concurring opinion. Toward the end of the majority opinion, Judge Bazelon suggests that a “legislative rulemaking with attendant notice and comment procedures” could redress the “difficulty” arising from the decision that a manufacturer may now avoid recall by protracted litigious strategems. Maj.Op. at 998. Yet throughout its opinion the majority reiterates its view that the drafters of section 207 intended that vehicles and engines beyond their useful lives at the time of repair need not be remedied by the manufacturers. See, e.g., Maj.Op. at 988-989 (“vehicles beyond their useful lives have no nonconformity to be remedied”);11 id. at 989 (“the EPA invites manufacturers to indulge in fact-specific controversies concerning whether a given car, beyond its useful life when presented for repair, experienced nonconformity during its useful life ....”);12 id. *124at 991 (“a blanket rule disregarding the age of the car when presented for repair in effect requires the manufacturer to make an older car meet standards that Congress intentionally required only younger cars to meet .... the EPA rule [therefore] exceeds the limits of permissible statutory interpretation”).13 It is therefore difficult to see *125how the same section could authorize the legislative rule suggested by the majority— to toll the “useful life” of the car at the time of EPA notification of noncompliance — or the “mathematical” rule suggested by Judge Wilkey — to include in remedial plans all cars and engines within their useful lives at the time of the EPA notice. Either one would require the repair of vehicles beyond the age limits set by Congress, and so violate the basic tenets of the panel’s rationale.
Judge Wilkey’s concurrence is equally puzzling. He extends the manufacturer’s repair obligations to encompass only those cars within their useful lives at the time the EPA issues a notice of nonconformity. To arrive at this conclusion, he parses section 207(c) “workpng] backward,” and finds that a remedial plan must provide for only “the vehicles or engines with respect to which such notification is given.” Conc.Op. at 999. Judge Wilkey, however, stops his backward trek through the statute too soon. Under section 207(c), EPA must give notice with respect to a “class or category of vehicles or engines” found not to conform to emission standards during their useful lives. The statute thus mandates classwide notice without limitation, and requires the manufacturer to repair all cars and engines “with respect to which [such] notice is given.” Judge Wilkey nonetheless declares as if by fiat “[t]here can be no ‘nonconformity’ by automobiles which, at the time of EPA determination and notice have passed their useful lives.” Id. In the face of a statute that requires notices of nonconformity to be sent with respect to entire classes of cars— some members of which might already be beyond their useful lives at the time of notice — one may properly wonder: why not? By the same token, the statutory language does not compel Judge Wilkey’s notion that “[notification of nonconformity can only be given to manufacturers with regard to cars which are obligated to conform to emission standards .... ” Conc.Op. at 1000. The statute may fairly be read to require classwide notice, regardless of whether some members of the class have exceeded their useful lives.
Moreover, Judge Wilkey’s notion that there can be no emission standards for cars beyond their useful life, id., is directly at odds with his proposal that every ear “within its useful life on the date of the EPA notice” should be repaired at the manufacturer’s expense, no matter what the car’s age or mileage at the time of repair, id. Under Judge Wilkey’s proposal, many cars exceeding their useful lives at the time the recall is implemented would nevertheless be repaired pursuant to a remedial plan. How and why, under his original notion, should a car to which “no [emission] standards,” apply and for which “there can be no nonconformity with emission standards,” id. be part of an EPA-mandated remedial plan?
Finally, the majority objects to the EPA rule on the ground there is no adequate method to determine whether an overage car was ever in violation of the standards during its useful life. See Maj.Op. at 990 (“If the car is not presented for repair until it has exceeded its useful life, how will the timing of the onset of excessive emissions be established?”). Yet, the panel’s legislative rule and the concurrence’s “mathematical” rule would both result in the. repair of cars and engines exceeding their useful lives without any attempt to establish whether emission standards violations occurred during their useful lives. Both rules suggest to me that Judges Bazelon and Wilkey felt compelled pragmatically to find some escape from the statutory straight jacket in which they had laced themselves.
Unfortunately, neither succeeds in providing a principled exception to their basic, and I believe misguided, notion that only individual vehicles within their useful lives at the time the recall is implemented or the notice is given can suffer from a “nonconformity” to be remedied by the manufacturer’s plan. Yet, in the absence of such an exception, the majority admits that the re*126call system will be “rendered useless.”14 Maj.Op. at 997. Like the EPA, I do not submit to the notion that only individual vehicles within their useful lives at the time of recall (or notice) can be “nonconforming” so as to come within the scope of the remedial plan. Congressional enactments should be interpreted to avoid impediments to clear congressional purpose. Section 207 accordingly should be interpreted in a way that can sustain a workable recall system: classes and categories of cars that have exhibited substantial nonconformity during their useful lives should be subject to recall.
To sum up, I find nothing in the plain language, nor in the legislative history of the Clean Air Act Amendments to contradict the EPA’s reasonable interpretative rule. The EPA rule presents a practical solution to the implementation of the clear congressional purpose of achieving effective automotive emission controls. The majority opinion, by its own admission, seriously detracts from this overarching purpose.15 Accordingly, I believe the majority, in invalidating the EPA rule, has transgressed the appropriate standards that limit judicial interference with an agency’s reasonable actions to effectuate an important national policy.
I respectfully but emphatically dissent.
. Courts should pay special deference to the agency’s interpretation when, as here, (a) the agency is interpreting a statute it is charged with administering, (b) the interpretation has been consistently adhered to, see infra note 5, (c) Congress has acquiesced to the administrative interpretation, see infra at 1003-1005, and (d) the statute gives the agency substantial discretion in administering and designing an enforcement scheme, see 42 U.S.C. § 7541(c)(1), (2). See National Wildlife Fed’n v. Gorsuch, 693 F.2d 156, 166-69 (D.C.Cir.1982) (enumerating “[t]he usual factors . . . (regulatory agency, consistency, contemporaneous construction, expertise, congressional acquiescence, thoroughness) [that] generally support giving great deference to EPA’s interpretation”); Wilderness Soc’y v. Morton, 479 F.2d 842, 864-67 (D.C.Cir.) (en banc), cert. denied, 411 U.S. 917, 93 S.Ct. 1550, 36 L.Ed.2d 309 (1973).
. The EPA explained with specificity the purposes of section 207 when the interpretative rule was promulgated, and warned that those purposes could be undermined in the absence of the rule:
The recall program has two objectives: 1) To assure that manufacturers repair vehicles which are exceeding the emission standards if maintained and used and the nonconformity occurs within the useful life of the vehicles, and 2) to encourage manufacturers to build durable emission-related components to assure that vehicles will not manifest excessive emissions during their useful lives. Both of these objectives are frustrated by an interpretation of useful life which limits manufacturers’ liability only to vehicles which are within their useful life at the time of repair.
45 Fed.Reg. at 36,397.
. The majority suggests that EPA may redress this “difficulty” through the adoption of “a legislative regulation providing that the useful life of vehicles in a class be tolled at the time the administrator notifies the manufacturer of the nonconformity .... ” Maj. Op. at 998 n. 79. However, contrary to the majority’s belief that “the Administrator has substantial discretion in defining ... the useful lives of vehicles,” id, the statute appears to limit that discretion to exclude “light duty vehicles and light duty engines.” 42 U.S.C. § 7521(d)(1); see Harley-Davidson Motor Co. v. EPA, 598 F.2d 228, 230 (D.C.Cir.1979) (Bazelon, J.). Passenger cars, of course, are light duty vehicles.
.As the EPA, when issuing the interpretative rule, emphasized: “interpreting section 207(c)(1) as imposing a useful life limitation on vehicles eligible for repair under a remedial plan could severely limit the number of nonconforming vehicles repaired pursuant to recall orders, could seriously impact ambient air quality, and would frustrate the intent of Congress.” 45 Fed.Reg. at 36,398.
. The majority appears to believe that the exemption excluding vehicles not “properly used and maintained” from the manufacturer’s recall repair obligation somehow undercuts the EPA’s class based approach. See Maj. Op. at 997 n. 76. This exemption — unlike the exemption the majority creates — is established by express statutory language. See 42 U.S.C. § 7541(c)(1). The majority neglects the significant difference between statutory language and judicial innovation.
. The majority attempts to make light of the EPA’s historical adherence to its current interpretation. The majority asserts that the EPA interpretation has only “a lifespan barely exceeding one year” because the sole controversy over the interpretation occurred in 1979. But, as EPA observed when it issued its interpretative rule, “[i]n the past, manufacturers have not conditioned a vehicle’s eligibility for recall repair ... on the basis of the vehicle’s age or mileage.” 45 Fed.Reg. at 36,397. Rather than diminishing the rule’s status as a longstanding EPA interpretation, the absence of any prior controversy over the repair of cars past their useful lives demonstrates the reasonableness of EPA’s interpretation of its own regulatory scheme. See, e.g., Esquire, Inc. v. Ringer, 591 F.2d 796, 801 (D.C.Cir.1978) (Bazelon, J.) (administrative interpretation deserves “controlling weight,” particularly when it “has been consistently followed for a significant period of time”), cert. denied, 440 U.S. 908, 99 S.Ct. 1217, 59 L.Ed.2d 456 (1979); DeLano v. United States, 393 F.2d 517, 521, 183 Ct.Cl. 379 (1968) (“A strong indication of the reasonableness of that [administrative] construction is the fact that [the regulated parties] never challenged it” even though it was “consistently maintained by the agency.”). Apparently, virtually every manufacturer engaging in a recall has voluntarily included older cars in its own remedial plans.
The majority mistakenly claims that “manufacturers in previous recalls have failed to raise the question of liability for repair of cars beyond their useful lives because the involvement of such vehicles in the recalls has been de minimis.” Maj. Op. at 985 n. 40 (emphasis in original). The majority has lost sight of the facts. Despite the majority’s view that “virtually all” recalls involved “tiny percentage^] of older cars,” id., in six out of the fifteen recalls described in detail in the record, see J.A. at 278-96, the EPA issued a recall notice to the manufacturer 34-55 months after the cars were on the market. Under EPA’s method of calculating the percentage of cars recalled that were beyond their useful lives, see J.A. at 275 (endorsed by majority at Maj. Op. at 985 n. 40), these recalls involved large quantities of older cars. For example, the Pontiac recall, initiated in 1979, involved 1975 model year cars, 54% of which were beyond their useful lives. See J.A. at 293. Moreover, almost 30% of the 1976 Pontiacs involved in that recall had exceeded their useful lives at the time of manufacturer notice. Similarly, in 1978 EPA initiated a recall that included 1975 Fords, approximately 28% of which had exceeded their useful lives. See J.A. at 289. Also, in 1978 the EPA began a recall that included 1974 AMC cars sold in California, approximately 56% of which were beyond their useful lives. See J.A. at 291-92. Any manufacturer who “prophetically foresaw” the majority’s position, Maj. Op. at 13 n. 40, believing these recalls exceeded the legal scope of coverage, could reasonably have been expected to make an objection.
At least three other recalls included substantial numbers of older cars. See J.A. at 280 (1974 Pontiacs; approximately 22% beyond useful lives); J.A. at 288 (1975 Fords; approximately 16% beyond useful lives); J.A. at 296 (1977 Buicks; approximately 28.5% beyond useful lives). The majority objects that some of the recalls mentioned herein “were incomplete at the time the record in this case was submitted (thus leaving the court without information concerning whether 5/50 limitations were ultimately imposed).” Maj. Op. at 985 n. 40. Only two of the recalls mentioned — the 1977 Buick recall, and the AMC recall — fit this description. In both cases, the manufacturer had already submitted a remedial plan without asserting the 5/50 limitation. See J.A. at 291-92, 296. Moreover, the EPA had already approved the AMC remedial plan as to six-cylinder vehicles. See J.A. at 291.
Finally, the majority argues that “even if 20% of the cars in the class were beyond their useful lives at the time of owner notification, ... a 20% response rate could be expected for those cars, [and] only 4% of the cars presented for repair could be expected to be beyond their useful lives.” Maj. Op. at 986 n. 40. Thus the majority declares that even 20% of the recall class is “de minimis.” Such statistical sport, of course, ignores the fact that the manufacturer incurs heavy costs — both financial and as to good will — simply by issuing its notice to owners. Moreover, under the majority’s reasoning virtually no recalls could involve a significant percentage of older vehicles. As time goes by, the percentage of older cars in the recall class rises, see J.A. at 275, but the response rate declines commensurately, see J.A. at 298. In fact, following the majority’s reasoning, GM had no good reason to raise its challenge in this case. At the time of the EPA notice, only approximately 13.5% of the Cadillacs in the recall class had exceeded their useful lives. At the time that GM first raised the 5/50 objection, a 35% response rate could have been expected. See J.A. at 298. Accordingly, following the majority’s methodology, only 4.7% of the older Cadillacs in the recall class would actually have been repaired. Yet in this case the manufacturer saw fit to pursue this challenge; I think it reasonable therefore to believe that other manufacturers would have done likewise in the past.
. As noted above, the Senate bill included no five-year limit on the “useful life” of cars and engines. The Committee, therefore, anticipated that some cars could be many years old and yet still be within their useful lives.
. The House bill contained no “recall” provision whatsoever. See H.Rep. No. 1146, 91st Cong., 2d Sess. 11-13 (discussion of “Automotive emission control provisions”). The House bill included only a design warranty requirement, see id. at 998 (section 206(e) of H.R. 17255), and an EPA authorization to halt manufacture of new cars if it determined that the engines or vehicles being produced did not comply with the standards, see id. at 997 (section 206(b) of H.R. 17255).
. The majority suggests that the Congress’ rewrite of the recall provision in conference was a meaningless gesture, signifying nothing. See Maj. Op. at 993-994 n. 61. While the urge is strong to pass this one by (“Let the long contention cease! Geese are swans and swans are geese!” M. Arnold, The Last Word), I will respond briefly.
Attempting to transform the absence of comment on a conference committee amendment into a positive indication of legislative intent to make no change contravenes two established principles of statutory construction: (1) “an amendment indicates that [the legislature] thereby intended to change the original [bill] by creating a new right or withdrawing an existing one,” 1A C. Sands, Statutes and Statutory Construction § 22.30, at 178 (4th ed. 1972), and (2) “[t]he presumption against interpreting a statute in a way which renders it ineffective is hornbook law,” FTC v. Manager, Retail Credit Co., 515 F.2d 988, 994 (D.C.Cir.1975). Moreover, the search for significance in legislative silence is at best a hazardous enterprise. See, e.g., Scripps-Howard Radio v. FCC, 316 U.S. 4, 11, 62 S.Ct. 875, 880, 86 L.Ed. 1229 (1942). When Congress does not say anything other than in the statute itself, that is where we look for guidance. Thus, the majority cannot reasonably rely on congressional silence to invalidate an otherwise reasonable EPA rule, especially when, according to its own admission, it “render[s] useless” the statutory provision itself.
.The majority relies almost entirely on this one passage to support its central arguments as to congressional intent. See Maj. Op. at 992-996. It does cite a few additional passages as evidence that “Congress intentionally limited the duration of a manufacturer’s liability for a vehicle’s conformity to standards to a five-year/fifty thousand-mile period....” Id. at 996 (emphasis omitted); see also id. at 996-997 n. 76 (reiterating same point). These additional passages, however, demonstrate nothing more than a congressional purpose— clearly evidenced by the statutory language, see 42 U.S.C. § 7521(d) — to define and limit the “useful life” term as it legitimately applies throughout the statute. The question presented by this case, not solved by the definition of “useful life,” is whether a member vehicle *123or engine of a recalled class that has exceeded its useful life should nevertheless be repaired by the manufacturer.
. This semantic argument assumes away the plain language of section 207. See supra at 1002-1003. It is evident from the statutory language and legislative history, see supra at 1002-1005 that Congress intended to provide classwide remedies for classwide design or performance defects that showed up during the useful life of the cars listed as representative samples of the class. A defective class — its members — can therefore be deemed “nonconforming.”
. As demonstrated supra at 1002-1003, the Congress authorized EPA to order recall of a vehicle once it determines that (1) a class of cars exhibited nonconformity during their useful lives, and (2) the particular car belongs to that class. The first determination requires that the EPA test sample consist of cars that have not exceeded their useful lives. The EPA then may recall any car within the class represented by that sample.
The EPA’s rule absolves manufacturers of the responsibility “to remedy the nonconformity of a vehicle which, although part of the recall class, experienced nonconformity only after expiration of the vehicle’s useful life.” 45 Fed.Reg. at 36,397 n. 2. The majority finds fault with this so-called “concession,” saying that it “erodes [EPA’s] class-based theory” and “offers little relief to manufacturers in practice.” Maj. Op. at 990.
I find this rule perfectly consistent with the statutory scheme. Cf. Maj. Op. at 989 n. 50. Congress obviously intended EPA to conduct tests on representative samples and to recall cars on the basis of the results. Unless Congress wanted EPA to test every car in a class, Congress was willing to allow such a statistical inference. Contrary to the majority’s unnecessarily rigid — even stolid — view of my reasoning, see id. (characterizing “the dissent’s position that ail vehicles which are part of a nonconforming class are subject to repair at manufacturer expense”) (emphasis in original), I believe the EPA sensibly interpreted the statute’s statistical inference to permit exceptions upon an adequate showing by the manufacturers. Thus EPA’s rule simply permits the manufacturers to rebut this statistical inference.
The majority also criticizes the statistical inference by questioning the adequacy of EPA’s sampling. See Maj. Op. at 990. This criticism, of course, does not undercut EPA’s interpretative rule. Instead, it merely questions EPA’s implementation of the rule in this case. I note that General Motors has not questioned the adequacy of the EPA testing in this case. Indeed, GM in its brief stated that subsequent to the EPA tests, “GM and EPA worked out a test program, to be done by GM with EPA’s participation .... GM concluded that a noncompliance existed and suggested a repair method in February, 1977.” GM Brief at 35-36 (emphasis added).
Finally, the majority decries EPA’s rule because “such a showing [of compliance within the useful life] may be impossible with respect to cars that have exceeded their useful lives when presented for repair.” Maj. Op. at 991. Given the evident congressional intent to trigger recalls by the testing of classwide samples, I believe the burden of exemption from the recall repair obligation properly falls upon the manufacturers. In fact, I see no other practical way of implementing the majority’s own pro*124posed “legislative rule” or the rule suggested in Judge Wilkey’s concurrence. Under either proposal, cars within their useful lives at the time of the EPA notice of noncompliance would be repaired at the manufacturer’s expense even though they exceeded their useful lives by the time the recall actually occurred. See Maj. Op. at 998 n. 79; Cone. Op. at 1000. Either rule would have to presume that some cars, out of compliance and past their useful life at the time of repair, violated the emission standards during their useful life.
. EPA has explained that GM would be required to perform only the same repair on the “older cars” that GM must perform on the “younger cars.” See Maj. Op. at 998. The majority condemns the EPA rule, so read, for mandating “manipulation[sj” that do not “remedy a nonconformity as the statutory language clearly contemplates,” id. at 999 (emphasis omitted).
The majority, in hypothesizing about possible future problems in the implementation of EPA’s rule, not presented by this case, exceeds the proper scope of an inquiry into “the validity of the rule.” Maj. Op. at 991 n. 58. The rule requires manufacturers simply to devise plans for the “remedy [of] all properly maintained and used vehicles which experienced the nonconformity during their useful lives .... ” 45 Fed.Reg. at 36,398. Such a requirement is neither per se unreasonable nor invalid on its face. The “remedy” required by the rule for older cars may well not turn out to be as burdensome as the majority seems to believe. See Association of Nat’l Advertisers, Inc. v. FTC, 617 F.2d 611, 621 (D.C.Cir.1979) (“it may be that this provision will unlawfully burden rights ... but in this situation, when the precise operation and impact of the requirement are unsettled, it is best for the judiciary to stay its hand until the provision in fact does result in the consequences appellants predict”) (emphasis in original), cert. denied, 447 U.S. 921, 100 S.Ct. 3011, 65 L.Ed.2d 1113 (1980).
Furthermore, the application of the rule in this case is unquestionably reasonable. The remedial plan before us involves a few turns of a screwdriver, and it is not for this court to conjure up more complex remedial situations. See, e.g., National Automatic Laundry & Cleaning Council v. Shultz, 443 F.2d 689, 703 (D.C.Cir.1971) (courts should avoid decisions “that cannot be meaningfully analyzed without the aid of concrete factual backgrounds”); National Wildlife Fed’n v. Goldschmidt, 677 F.2d 259, 263 (2d Cir.1982) (“A decision by us at this stage would resolve a dispute about a hypothetical highway. Courts have no business adjudicating the legality of non-events.”). The EPA in oral argument attested to its flexibility in devising reasonable remedial schemes to fit other, more problematic, design and performance violations. Whether the rule will be applied reasonably to such violations should be left to future cases. See, e.g., Abbott Laboratories v. Gardner, 387 U.S. 136, 148-49, 87 S.Ct. 1507, 1515-16, 18 L.Ed.2d 681 (1967) (courts should not interfere with administrative decisionmaking until “its effects [are] felt in a concrete way”); National Automatic Laundry, 443 F.2d at 703 (observing “the need for restricting [judicial] rulings to broad questions fairly presentable in a litigation, without reaching questions of particular application that warrant separate consideration at a later time, if and when they arise”). The EPA rule does not set out any particular repair schemes; accordingly, this court’s review of “the validity of the rule” does not, in my view, legitimate its current foray into purely theoretical future implementation problems.
If the lack of a decision on this question created substantial hardship to private regulated parties, then judicial intervention might be proper. See, e.g., Abbott Laboratories, 387 U.S. at 149, 87 S.Ct. at 1515; Gulf Oil Corp. v. United States Dept. of Energy, 663 F.2d 296, 311-12 (D.C.Cir.1981). But the recall system imposes no risk upon the auto manufacturers that their rights could be prejudiced prior to judicial review of some future recall. Thus, I do not believe the majority properly exercises its reviewing function when it today invalidates a rule on the basis of problems not squarely presented to this court, and without affording EPA the opportunity to find methods of addressing such problems in a real — not hypothetical — situation.
I also note that these same remedial problems would plague the majority’s “legislative rule” and Judge Wilkey’s proposed “mathematical” solution. Both approaches would likewise require the remedial scheme to include some cars that have passed their useful lives, and so are equally obliged to address what standards should be employed in the repair of such older cars. In fact, many of the same problems inhere in remedying a class of cars all the members of which are still within their useful lives. Should the car with 49,999 clocked miles be repaired in the same way or according to the same standard as the car with 100 miles? Again, this is a question for another day. Given Congress’ purpose to ensure that manufacturers build cars to conform with emission standards over their entire useful lives, however, I find nothing outrageous in requiring manufacturers to repair at some *125point the very defects that caused a class of cars to fail to meet those standards during their useful lives.
. The majority cites other enforcement mechanisms created by the Clean Air Act, as if their existence excuses the gutting of section 207(c). See Maj. Op. at 997 n. 78. However, the certification provisions of the Act, 42 U.S.C. § 7525(a), (b), do not create a remedy for consumers who have already purchased defective vehicles or engines; instead, under the provision the EPA may only revoke the classwide manufacturing certificate, thereby preventing further future sales from the defective class of items. In addition, the performance and design warranty provisions, id. § 7541(a), (b) do not employ EPA oversight and testing capabilities; instead, they rely on individual consumers to detect that their cars are exceeding emission standards. Thus, the recall provision occupies an important position in the enforcement scheme: it combines the EPA role of conducting investigations of classes of vehicles and engines (also present in the certification provisions) and the purpose of policing on-the-road vehicles and engines (also present in the warranty provisions).
. In a final assault, the majority peremptorily declares this case to be “virtually moot.” Maj. Op. at 999 n. 81. The meaning and legal significance of “virtual mootness” is, of course, mysterious; for if this case were “truly moot,” the entire majority opinion would be dictum. In any case, the majority teases the auto manufacturers with yet another legal doctrine with which to circumvent the clear purposes of the Clean Air Act. This final aside, id., seems particularly inappropriate considering this court’s own contribution to the long pendency of this case.