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Heavy-duty vehicles account for approximately 30 percent of the oxides of nitrogen (NOx) and 65 percent of the particulate matter (PM) emissions from the entire California on-road fleet, despite the fact that these vehicles comprise only 2 percent of the same. To meet legislative mandates to reduce excess smoke emissions from in-use heavy-duty diesel-powered vehicles, the Air Resources Board (ARB or Board) adopted, in December 1997, amendments to the regulations governing the operation and enforcement of the Heavy-Duty Vehicle Inspection Program (HDVIP or the “roadside” program) and the Periodic Smoke Inspection Program (PSIP or the “fleet” program). The initial roadside program was adopted in November 1990 in response to Senate Bill (SB) 1997 (stat. 1988, ch. 1544, Presley), and enforced from 1991 to 1993. It was suspended in October 1993, when the Board redirected staff to investigate reformulated fuels issues.

The EPA has proposed revising the Federal Test Procedure (FTP) used to evaluate compliance with emission standards. The revisions involve the addition of two new driving cycles, one of which (US06) includes high speeds and high acceleration rates. EPA has also proposed the operation of the air-conditioner on the “hot stabilized” cycle and the second (SC01) of the two new cycles. In order to meet emission standards on the new procedure, revisions to the emission control technology currently employed in cars and light trucks is required. In this study, we evaluated the range of potential changes to “engine out” emissions required, as well as requirements for catalyst improvements to withstand the higher exhaust temperatures and space velocity. Analysis of available test data suggested that power enrichment must be very nearly or completely eliminated to meet standards on the US06 test cycle.

Manufacturers have used a number of alternative emission control technologies to meet the emission standards for 1981 and later model years. Each technology type can have malperformances that lead to high emissions, but the ability of inspection/maintenance short tests to identify high emitters varies considerably by technology. In this study, the relationships between malperformance types, FTP emissions and short test emissions were identified for several major technology types, using data from the EPA Emission Factor data base. Based on these relationships, methods to enhance the effectiveness of I/M tests are suggested. The analysis indicated that the most important factor governing the ability of any I/M short test is the presence of absence of secondary air. The short tests were found to be incapable of recognizing any malperformance except severe misfire if secondary air was present.

In spite of stable emission standards in force since 1981, automotive emission control technology has contined to evolve at a very rapid pace. In this paper, a very detailed forecast of emission controls for U.S. fleet of new cars is described. Forecasts of emission control technology mix by every combination of fuel system/catalyst system/secondary air system/EGR system are derived. Data on the fleet mix of emission controls is presented for the 1982-1990 time frame. Each of these different types of systems have different failure modes that lead to significantly different malperformance model emissions. Using data derived from emissions tests of vehicles that were intentionally disabled, estimates of the emissions from malperforming vehicles of the future are drawn. The estimates may form the basis of in-use emissions forecasts in the future.

This paper evaluates the technical and programmatic issues associated with the design of a California state-sponsored consumer information program on automotive fuel saving products. It identifies relevant products, outlines procedures for testing their technical merits, and discusses testing facilities and available test results. Based on these results, aftermarket devices (hardware), fuel efficient lubricants, and radial tires are evaluated for fuel conservation potential and cost effectiveness. The paper discusses various options for a consumer information program, including information dissemination, advertising disclosure, sales regulation, and liability reform. Programmatic benefits and costs are quantified for most options.

This paper assesses three factors affecting projections of passenger car fuel consumption: 1) "fuel-switching" by consumers; 2) new car fuel economy trends through 1995; and 3) the on-road fuel economy characteristics of older cars. Surveys of monthly household motor fuel purchases in 1978-1981 are used to demonstrate a significant correlation between vehicle age and trends in "misfueling". Projections of new car fuel economy are derived using a technology-oriented model previously developed for the U.S. Department of Energy (DOE). The forecasts are sensitive to fuel prices, consumer discount rates, and technology payback periods. The paper discusses the effects of changes in vehicle use intensity and odometer on the in-use fuel economy of older cars. Information also is presented on the in-use fuel economy of pre-MY1975 vehicles. The paper concludes with an assessment of the effects of these fuel economy and fuel switching trends on future automobile fuel demand.

This paper addresses fuel economy standards that can be obtained in 1985 for two-wheel drive LDT's using existing technology. To estimate the fuel economy, the fleet of LDT's is first segmented into market classes based on the concept of utility. The 1985 sales share of each class is predicted from an extrapolation of current trends as well as published sales forecasts. The 1985 fuel economy of each market class is projected using 1) MY '80 truck technology and fuel economy as a baseline, 2) a regression equation that allows an estimate of fuel economy based on the weight, drag, and engine displacement, and 3) the addition of fuel-efficient technologies. Estimates of weight reduction and new model introduction within each market class were derived from published manufacturers' plans. Based on this methodology, this analysis concludes that a fleet fuel economy in excess of 24/25 mpg is feasible for 1985 without/with the use of diesel engines.

The accurate sampling and characterization of automotive particulate emissions is important to quantify any potential threat to human health. EPA has issued a draft recommended practice to measure the total weight of particulates emitted over the FTP, but there are many parameters that are uncontrolled or can be varied within the scope of the draft recommended practice. The parameters were separated into two categories: those affecting particulate formation and those affecting particulate sampling. The variables under the former category were identified as tailpipe conditioning and heat transfer, dilution ratio, and mixing rate. Test data on the effects of each of these variables on measured particulate emissions are presented and analyzed. The variables under the latter category were identified as the tunnel configuration, sample probe and sample line, and the type of filter used for sampling.

The cost effectiveness of the current automobile fuel economy standards program is evaluated. A life cycle cost analysis is used to quantify the costs and benefits of fuel economy improvements stimulated by the program. The magnitude of these improvements is estimated by measuring the difference between the standards and a baseline “no standards” case. Due to the uncertainty associated with technology cost estimates, two scenarios are developed to bound the cost of fuel economy improvement; an “optimistic” scenario using technology cost and MPG gains documented by DOT and another “pessimistic” scenario based on conservative technology cost and fuel economy estimates. A review of fuel economy legislation concludes that marginal cost effectiveness to the nation be a significant criterion for setting future fuel economy standards.