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SUMMARY AND CONCLUSIONS In legislating the Clean Air Amendments of 1970, the Congress asked the Environmental Protection Agency (EPA) to contract with the National Academy of Sciences (NAS) to conduct a comprehensive study and investigation of the technological feasibility of meet ing the motor vehicle emissions standards prescribed in accordance with the law . In responding to this request, pursuant to a contract w ith the EPA, the Academy established a Committee on Motor Vehicle Emissions (CMVE) and charged it with the conduct of this study. In its investigation of "technological feasibility, " the CMVE addressed the following issues: 1. Determination of the feasibility of developing and designing an emissions control system that would enable compliance with the legally estab lished emissions standards as judged by the certification procedures prescribed by the EPA. 2. The feasib ility of mass producing those systems of promising design. 3. The projected performance of such emissions control systems in customer usage, includ ing the requirements for maintenance necessary to assure continuing reliab ility . 4. The costs, per vehicle, associated with acqui sition, maintenance, and operation of the emissions control system . - 1 - Digitized byGoogle
In the course of its work, the Comm ittee has examined the v ariety of approaches of manufacturers and others to the problems relating to emissions control. At the ttme of this report, progress toward resolut ion of these problems in the four aspects listed above, although rapid, is uneven and uncertain, and the outlook toward 1975 and 1976 is not yet clear. Moreover, the rapid pace of that progress complicates judgment concerning the most appropri ate course of action for attainment of the standards required by the law . !2E 1975 model year light -duty motor vehicles, the Committee concludes that - - 1. Four types o f systems will meet the prescribed emissions standards dur ing certification testing. These are: the modified convent ional engine equipped with an oxidation catalyst, the car bureted strat ified-charge engine, the Wankel engine equipped with an exhaust thermal reactor, and the diesel engine. For the catalyst system, one catalyst change must be permitted during the 50,000 mile durability testing for certification, and fuel with a suitably low level of c atalyst poisons must be allowed . In determining whether vehicles mass-produced comply with an outstanding certifi cate of conformity under Section 206 of the Clean Air Act, p�ov isions must be made for averaging of emission test results within a vehicle and engine class. 2. Vehicles incorporat ing these systems can be mass produced in great enough volume to satisfy, in aggregate, the expected d emand for vehicles in model year 1975. - 2 - Digitized by Coogle
3. It is �portant for two reasons that a suitable maintenance and inspection system be established for vehicles in use by the public . F irst, there are no data concerning the deterioration of emission-control systems under conditions of customer use, and the Committee believes that the certification procedure alone is not a sufficient indicator of system durab ility. Even if it is demonstrated that properly maintained vehicles can comply with the standards under condi tions of customer use, an adequate vehicle mainten ance and inspection system will be required to assure that most vehicles will meet the standards when used by the general public; this is especially important for catalyst-equipped vehicles . Second, if it is determined that a substant ial number o f any class of vehicles or engines, although properly maintained and used, is not meeting the stan dards in use, Section 207 (c) of the Clean Air Amedments empowers the Administrator of EPA to require the manu facturer to submit a plan for remedying the nonconformity . Under such a plan, the manufacturer is required to correct only those vehicles or engines which have been properly ma intained and used . 4. The average increase in sticker price due to the emissions control system of a catalyst-equipped vehicle is.esti mated to be $ 160 above a current (1973) vehicle and $230 above a 1970 model year vehicle. Except for the d iesel engine, lesser increases are expected for the other emission-control systems, when comparing vehicles of similar size and type. - 3 - Digitized byGoogle
Model year 1975 vehicles using Wankel engines or catalyst-equipped spark-ignition piston engines will use significantly more fuel than their 1973 counterparts . Carbureted stratified-charge engines will suffer only a slight fuel penalty; and the diesel engine will offer improved fuel economy, enough to compensate for its high initial cost within a few years of driving . !2£ 1976 model year light-duty motor vehicles, the Comm ittee concludes that - - 1. Five control systems n ow in early stages of development have met the 1976 emission standards at low mileage . These are: the modi fied conventional engine equipped with dual catalysts, or with dual catalysts plus thermal reactor, or with two thermal reactors and a reduction catalyst, or with a three-way catalyst and electronic fuel injection , and the stratified- charge engine employing fuel injection and equipped with an oxidation catalyst . It is possible, but not certain, that some of these sys tems may prove to be certifiable for 1976, contingent upon the acceptance of the same provisos previously mentioned for 1975 model year vehicles . More importantly, the recently developed carbureted stratified -charge engine, after 50, 000 miles of durability test ing on a compact car, has achieved well over the 90 percent reduction in hydrocarbon and carbon monoxide emis sions called for in the Act and about 83 percent reduction in NO x⢠The Comm ittee bel ieves that this engine will be certi fiable for 1976, at least in smaller engine sizes . - 4 - Digitized byGoogle
2. If certifiable, vehicles incorporating any of these systems can be mass-produced, but not necessarily in great enough volume to satisfy, in aggregate, the expected d emand for vehicles in model year 1976. 3. The Committee holds the same concerns for performance of 1976 vehicles in use as discussed above for 1975 systems. 4. The average increase in sticker price of a dual catalyst-equipped vehicle is expected to be $290 above a current ( 1973 ) vehicle, and $370 above a 1970 model year vehicle. Average annual costs of a dual-catalyst emissions-control system, including maintenance and fuel, with the increase in sticker price amortized over five years, is estimated to be $260 per year, compared with a 1970 model year vehicle. In contrast, the annualized costs for several other systems are esttmated to be less than $100. The Committee is greatly concerned about the trend of development of the 1976 control systems. The system most likely to be available in 1976 in the greatest numbers - the dual -catalyst system - is the most disadvantageous with respect to first cost, fuel economy, maintainability, and durability. On the other hand, the most promising system - the carbureted stratified -charge engine - which may not be available in very large numbers in 1976, is superior in all these categories. The Committee wishes to alert both EPA and the Congress to this development and believes that it warrants immediate attention. - 5 - Digitized byGoogle
