1
Introduction

In the United States, medium- and heavy-duty vehicles (MHDVs) consume a significant and increasing amount of fuel. In 2008 these vehicles consumed 26 percent of all U.S. transportation liquid fuels and 20 percent of all U.S. liquid fuels. MHDVs consumed 3.9 million barrels per day (mbpd), compared to total 2008 U.S. liquid fuel consumption of 19.5 mbpd.

Liquid fuel consumption by MHDVs has increased more rapidly—in both absolute and percentage terms—than consumption by other sectors, and the Energy Information Administration (EIA) forecasts that this will continue. EIA projects that in 2035 these classes of vehicles will consume 30 percent of all U.S. transportation liquid fuels and 23 percent of all U.S. liquid fuels. That total will represent 5.1 mbpd, compared with total projected 2035 U.S. liquid fuel consumption of 22.1 mbpd. Thus, the fuel efficiency of these classes of vehicles is of high and increasing importance (DOE, EIA, 2009c). Furthermore, in December 2009 the U.S. Environmental Protection Agency (EPA) formally declared that greenhouse gas (GHG) emissions endanger public health and the environment within the meaning of the Clean Air Act, a decision that compels EPA to consider establishing first-ever GHG emission standards for new motor vehicles, including MHDVs. If the United States is to reduce its reliance on foreign sources of oil, and reduce GHG emissions from the transportation sector, it is important to consider how the fuel consumption of MHDVs can be reduced.

ORIGIN OF STUDY AND STATEMENT OF TASK

The National Research Council (NRC) Committee to Assess Fuel Economy Technologies for Medium- and Heavy-Duty Vehicles was formed in response to a congressional mandate to the National Highway Traffic Safety Administration (NHTSA), an agency of the U.S. Department of Transportation (DOT), under Section 108 of the Energy Independence and Security Act (EISA) of 2007. NHTSA was directed to contract with the National Academies to undertake a study and develop a report that evaluates medium- and heavy-duty truck fuel economy. The legislation also (1) mandates that NHTSA itself conduct a study on the fuel efficiency of commercial medium- and heavy-duty on-highway vehicles and work trucks and (2) mandates that NHTSA then conduct a rulemaking to implement a commercial medium- and heavy-duty on-highway and work-truck fuel efficiency improvement program.1

The language in Section 108 directs the National Academy of Sciences to address the following items in its report:

  1. an assessment of technologies and costs to evaluate fuel economy for medium-duty and heavy-duty trucks;

  2. an analysis of existing and potential technologies that may be used practically to improve medium-duty and heavy-duty truck fuel economy;

  3. an analysis of how such technologies may be practically integrated into the medium-duty and heavy-duty truck manufacturing process;

  4. an assessment of how such technologies may be used to meet fuel economy standards to be prescribed under section 32902(k) of title 49, United States Code, as amended by this subtitle; and

  5. associated costs and other impacts on the operation of medium-duty and heavy-duty trucks, including congestion.

In response to that language, the NRC developed a statement of task for the committee that directs it to:

  • Consider approaches to measuring fuel economy for medium- and heavy-duty vehicles that would be required for setting standards;

1

The legislation uses both the terms “fuel economy” and “fuel efficiency.” Fuel economy, generally miles per gallon or kilometers per liter, is commonly used in comparing the efficiency of light-duty vehicles, which have similar size and driving cycles. In comparing the fuel consumption of trucks and buses, its usefulness is limited, given there is a wide difference in mass and driving cycles. In particular, a metric is needed that reflects the work done by the vehicle. The committee discusses the appropriate metric for trucks and buses later in Chapter 1 and in Chapter 2.



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1 Introduction In the United States, medium- and heavy-duty vehicles also (1) mandates that NHTSA itself conduct a study on (MHDVs) consume a significant and increasing amount of the fuel efficiency of commercial medium- and heavy-duty fuel. In 2008 these vehicles consumed 26 percent of all U.S. on-highway vehicles and work trucks and (2) mandates that transportation liquid fuels and 20 percent of all U.S. liquid NHTSA then conduct a rulemaking to implement a commer- fuels. MHDVs consumed 3.9 million barrels per day (mbpd), cial medium- and heavy-duty on-highway and work-truck fuel efficiency improvement program.1 compared to total 2008 U.S. liquid fuel consumption of 19.5 mbpd. The language in Section 108 directs the National Acade- Liquid fuel consumption by MHDVs has increased more my of Sciences to address the following items in its report: r apidly—in both absolute and percentage terms—than consumption by other sectors, and the Energy Information (1) an assessment of technologies and costs to evalu- Administration (EIA) forecasts that this will continue. EIA ate fuel economy for medium-duty and heavy-duty projects that in 2035 these classes of vehicles will consume trucks; 30 percent of all U.S. transportation liquid fuels and 23 (2) an analysis of existing and potential technologies that percent of all U.S. liquid fuels. That total will represent 5.1 may be used practically to improve medium-duty and mbpd, compared with total projected 2035 U.S. liquid fuel heavy-duty truck fuel economy; consumption of 22.1 mbpd. Thus, the fuel efficiency of these (3) an analysis of how such technologies may be practi- classes of vehicles is of high and increasing importance cally integrated into the medium-duty and heavy-duty (DOE, EIA, 2009c). Furthermore, in December 2009 the truck manufacturing process; U.S. Environmental Protection Agency (EPA) formally de- (4) an assessment of how such technologies may be used clared that greenhouse gas (GHG) emissions endanger public to meet fuel economy standards to be prescribed under health and the environment within the meaning of the Clean section 32902(k) of title 49, United States Code, as Air Act, a decision that compels EPA to consider establishing amended by this subtitle; and first-ever GHG emission standards for new motor vehicles, (5) associated costs and other impacts on the operation of including MHDVs. If the United States is to reduce its reli- medium-duty and heavy-duty trucks, including con- ance on foreign sources of oil, and reduce GHG emissions gestion. from the transportation sector, it is important to consider how the fuel consumption of MHDVs can be reduced. In response to that language, the NRC developed a state- ment of task for the committee that directs it to: ORIGIN OF STUDY AND STATEMENT OF TASK • Consider approaches to measuring fuel economy for The National Research Council (NRC) Committee to medium- and heavy-duty vehicles that would be re- A ssess Fuel Economy Technologies for Medium- and quired for setting standards; Heavy-Duty Vehicles was formed in response to a congres- sional mandate to the National Highway Traffic Safety Ad- 1The legislation uses both the terms “fuel economy” and “fuel efficiency.” ministration (NHTSA), an agency of the U.S. Department Fuel economy, generally miles per gallon or kilometers per liter, is com- monly used in comparing the efficiency of light-duty vehicles, which have of Transportation (DOT), under Section 108 of the Energy similar size and driving cycles. In comparing the fuel consumption of trucks Independence and Security Act (EISA) of 2007. NHTSA and buses, its usefulness is limited, given there is a wide difference in mass was directed to contract with the National Academies to and driving cycles. In particular, a metric is needed that reflects the work undertake a study and develop a report that evaluates me- done by the vehicle. The committee discusses the appropriate metric for dium- and heavy-duty truck fuel economy. The legislation trucks and buses later in Chapter 1 and in Chapter 2. 

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0 TECHNOLOGIES AND APPROACHES TO REDUCING THE FUEL CONSUMPTION OF MEDIUM- AND HEAVY-DUTY VEHICLES • Assess current and potential technologies and estimate advantage of the expertise available on the committee to improvements in fuel economy for medium-duty and determine the extent to which the tasks could be addressed. heavy-duty trucks that might be achieved; It should be noted that the study does not address the use of • Address how the technologies identified in Task 2 alternative fuels to substitute for fossil-fuel-based diesel or above may be used practically to improve medium- gasoline. Domestic production of alternative fuels such as duty and heavy-duty truck fuel economy; biodiesel or natural gas could help to reduce demand for im- • Address how such technologies may be practically ports of petroleum or reduce emissions of greenhouse gases, integrated into the medium-duty and heavy-duty truck but these technologies and/or strategies are not addressed. manufacturing process; The committee provides some insights in Chapter 6 into the • Assess how such technologies may be used to meet unintended consequences that could arise from various ap- fuel economy standards; proaches that might be used to reduce the fuel consumption • Discuss the pros and cons of approaches to improving of vehicles. In addition, Chapter 7 explores the advantages the fuel efficiency of moving goods as opposed to set- and disadvantages of alternative approaches to reducing fuel ting vehicle fuel economy standards; and consumption, since many of these alternatives involve regu- • Identify the potential costs and other impacts on the latory changes, and Chapter 8 discusses fuel consumption operation of medium-duty and heavy-duty trucks. (See regulatory approaches. Appendix A for the full statement of task.) POLICY MOTIVATION The committee discussed these tasks with the DOT/NHT- SA representatives, as well as relevant congressional staff, The President and Congress have placed among the high- prior to and at the committee’s first meeting. The purpose est national objectives that of reducing petroleum imports. of these discussions was to explore what information and Despite efforts to wean the United States away from oil data could be made available to the committee and to take toward more acceptable fuels, it has become increasingly dependent on oil (Figure 1-1). FIGURE 1-1 Energy consumption by major source end-use sector, 1949-2008. SOURCE: DOE, EIA (2009b, p. 39). Figure 1-1 Energy use by major source end use sector.eps bitmap

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 INTRODUCTION While fuel consumed per mile by light-duty vehicles • Improved tire rolling resistance improved substantially between 1966 and 2007, fuel con- • Widespread implementation of electronic control fea- sumption of the average heavy-duty vehicle remained nearly tures such as road speed governors constant (Figure 1-2). However, this trend hides an important • Regulatory changes that allowed the use of longer, factor regarding trucking. The mission is not just to move wider, and taller trailers and higher maximum weight the truck and driver from one place to another but to deliver limits cargo. If total fuel consumed, total miles traveled, and total • Operational efficiency improvements by trucking com- tons shipped are considered for the United States as a whole, panies to reduce the amount of distance traveled with a U.S. average payload specific fuel consumption for the en- little or no load tire medium- and heavy-duty fleet can be calculated for this sector. Figure 1-3 shows the results of dividing the total fuel The improvement trend in this U.S. average payload specific consumed by the miles traveled and tons moved each year, fuel consumption for trucks has slowed in the past several to produce a fuel consumption per ton shipped and per mile years, at least in part due to the requirement to introduce driven (gallon/ton-mile) from 1975 to 2005. The amount new pollution controls for EPA-regulated air pollutants of fuel required to move a given amount of freight a given such as nitrogen oxides (NOx) and particulate matter (PM). distance has been reduced by more than half over this time The resulting changes to diesel engines have tended to period. This is a result of many factors, including: degrade their thermal efficiency. Gasoline engines also suffered degradation in performance when first required to • Improved efficiency of engines and drivelines meet regulated emission standards. The development of the • Improved vehicle aerodynamics three-way catalyst has allowed the recapture of much of the FIGURE 1-2 Motor vehicle mileage, fuel consumption, and fuel rates. SOURCE: DOE, EIA (2009a, Figure 2.8). Figure 1-2 Motor vehicle mileage...and fuel rates.eps bitmap

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 TECHNOLOGIES AND APPROACHES TO REDUCING THE FUEL CONSUMPTION OF MEDIUM- AND HEAVY-DUTY VEHICLES FIGURE 1-3 U.S. average payload-specific fuel consumption. SOURCES: Data from Federal Highway Administration, Highway Statistics Summary to 1995, Table VM-201A, and Highway Statistics payload specific VM-1,consumption.eps at http://www.fhwa. Figure 1-3 U.S. average (annual releases), Table fuel Washington D.C., available bitmap dot.gov/ohim/summary95/vm201a.xlw, accessed Feb. 25, 2010; total tons hauled from Bob Costello, American Trucking Association. lost performance; however, the three-way catalyst mandates required to reduce both fuel consumption and exhaust emis- that current gasoline engines must operate at stoichiometric sions. Light-duty vehicle manufacturers have already made air/fuel ratios. If effective lean air/fuel ratio aftertreatment significant improvements in reducing fuel consumption and systems could be developed, further reductions in gasoline even more progress in reducing vehicle emissions. The im- engine fuel consumption would be readily achievable. provements in light-duty vehicle (cars and light trucks) fuel Gasoline-powered medium- and heavy-duty vehicles have economy have been spurred in part by corporate average fuel followed the same historical fuel consumption and emission economy (CAFE) standards. For medium- and heavy-duty trends as the light-duty gasoline-powered vehicles. vehicles greater than 8,500 pounds GVW, no such standards The improved efficiency of both light- and heavy-duty currently exist. Emissions of NOx and PM from heavy-duty vehicles has been overwhelmed by an increase in annual vehicles will be significantly reduced by regulations that have vehicle miles traveled (VMT). VMT has grown more quickly gone into effect. However, reductions in fuel consumption of in the trucking sector than in the light-duty sector, resulting in the large medium- and heavy-duty vehicle fleet have not been medium- and heavy-duty vehicles taking up a growing share as impressive, partly because of the growth in the number of of total transportation-related petroleum consumption. miles driven by large trucks during the past decade. If current In fact, the U.S. transportation system relies nearly ex- trends continue, heavy vehicles will consume an important clusively on petroleum, as shown in Figure 1-1 (DOE, EIA, fraction of the fuel used for on-the-road vehicles. Therefore, 2009a). That dependence grows more each year, despite at- if the United States is to reduce its reliance on foreign sources tempts to substitute other fuels and energy sources. NHTSA’s of oil, it will be necessary to reduce the fuel consumption of programs to improve fuel consumption are generally con- medium- and heavy-duty vehicles. sistent with the EISA of 2007. The law also requires the The recession has interrupted the constant growth in DOT, for the first time in history, to establish fuel economy demand. The trucking industry and manufacturers continue standards for medium- and heavy-duty vehicles. The gross to lay off workers on a vast scale (something that does not vehicle weight ratings (GVWRs) for these vehicles range show in the 2007 data used throughout this report), and it is from 8,500 to more than 80,000 lb. (GVW and gross com- difficult to accurately extrapolate demand. bined weight [GCW] refer to gross vehicle weight, which is limited by regulation. GVWR is the manufacturer’s stated WEIGHT CLASSES AND USE CATEGORIES maximum GVW rating for a vehicle. The legal weight limit may be lower than the manufacturer’s rating in some cases. Figure 1-4 gives the reader an idea of the diversity of me- GVW and GVWR apply to single-unit vehicles and to the dium- and heavy-duty vehicles. It is based on the DOT clas- tractor in a tractor-trailer combination.) sification system using a truck’s GVWR. This information In addition, the use of fossil fuels for transportation was developed by Davis and Diegel of Oak Ridge National produces carbon dioxide, an important greenhouse gas that Laboratory for the U.S. Department of Energy (DOE) Trans- contributes to climate change; governments around the world portation Databook (Davis et al., 2009) and used extensively have taken action to reduce the use of fossil energy in their by the NESCCAF/ICCT (2009). The committee refers to that economies. The United States in particular is pursuing alter- material (Table 5.7) for the following observations: native sources of fuel and attempting to increase efficiency in oil usage, which will lower oil consumption and reduce • Class 1 and 2 vehicles lighter than 10,000 lb are greenhouse gas emissions. considered light trucks, such as pickups, small vans, As a result of these initiatives, vehicle manufacturers are and sport utility vehicles. They generally have spark-

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 INTRODUCTION FIGURE 1-4 Illustrations of typical vehicle weight classes. SOURCE: Davis et al. (2009, pp. 5-6). Figure 1-4 Illustrations of typical vehicle weight classes.eps bitmap ignited gasoline-fueled internal combustion engines, lightweight trucks grew 4.7 percent annually, while that of and more than 80 percent are for personal use. This passenger cars grew only 0.3 percent. Meanwhile, energy class of vehicle up to about 8,500 lb comes under consumption by heavy trucks increased 3.7 percent annually. CAFE requirements for cars. Class 2 trucks with Figure 1-3 displays this divergence in growth. It also displays GVWR above 8,500 lb are similar to Class 3 trucks. the underlying pattern that it is not so much the change in • Class 3 and above are primarily commercial vehicles. fuel economy as a dramatic increase in annual miles driven A mix of gasoline and diesel engines is used in Classes by heavy vehicles. The continuation of these trends is docu- 3 through 7, and diesel engines are almost exclusively mented in recent data through 2008 (NRC, 2008). used in Class 8. Trucks and trucking are important contributors to the na- • Classes 3 through 6 are medium- and heavy-duty ve- tional income, of course. According to the Economic Census hicles with single rear axles. of 2002 (the latest available), the truck transportation indus- • Classes 7 and 8 are heavy-duty vehicles with two or try consisted of more than 112,698 separate establishments, more rear axles. with total revenues of $165 billion (DOC, Census Bureau, • Class 8 combination trucks have a tractor and one 2005). These establishments employ 1.4 million workers, or more trailers and a GCW of up to 80,000 lb, with who take home an annual payroll of $47 billion. Truck and higher weights allowed in specific circumstances. bus manufacturing also accounts for a significant share of national income. According to the same census, light truck and utility vehicle manufacturers have total shipments of ENERGY CONSUMPTION TRENDS AND TRUCKING $137 billion. Heavy-duty truck manufacturing had sales of INDUSTRY ACTIVITY $16 billion. Another way to look at the trucking industry’s The number of medium- and heavy-duty trucks has economic contribution is to compare it with other industries increased substantially as the U.S. economy has grown. in the transportation sector, in which it accounts for about Over the period from 1970 to 2003, energy consumption by one-fourth of the sector’s total revenues (see Figure 1-5).

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 TECHNOLOGIES AND APPROACHES TO REDUCING THE FUEL CONSUMPTION OF MEDIUM- AND HEAVY-DUTY VEHICLES FIGURE 1-5 Total revenue of for-hire transportation services compared with revenue of other sectors of the transportation industry, 2002. SOURCE: DOC, Census Bureau (2005). Figure 1-5 For-hire transportation services...the transport.eps bitmap FACTORS AFFECTING IMPROVEMENTS IN FUEL tons per 100 miles. The lower the fuel consumption (FC) of CONSUMPTION the vehicle and the higher the payload the vehicle carries, the lower the LSFC. The payload has an important effect on the Medium- and heavy-duty trucks and buses are load- fuel consumption, and the average value used for potential carrying vehicles that are designed to perform work in an standards should be based on national data representative of efficient and timely manner. This makes them different from the class and duty cycle of the vehicle. light-duty vehicles. In the U.S. EPA light-duty fuel economy This report uses FC or LSFC data throughout except tests, the vehicle is tested at its empty weight plus the equiva- where fuel economy (FE) data are specified in the literature. lent weight of a couple of passengers. Later in the report, metrics for the fuel efficiency of me- For light-duty vehicles, load has only a modest impact dium- and heavy-duty vehicles sold and used in the United on fuel consumption. For example, a car with four passen- States will be discussed. How best to quantify this will be gers and luggage will use only slightly more fuel than the addressed consistent with U.S. national objectives to reduce same car with only a driver. For most light-duty vehicles, the nation’s reliance on oil. More detailed discussion of FE, the loaded weight is approximately 25 to 35 percent more FC, and LSFC is presented in Chapter 2. than the empty weight. However, for a heavy-duty vehicle, a loaded vehicle weighs more than double the empty weight. TASK ORGANIZATION AND EXECUTION Light-duty vehicles use the sales-weighted average of the fuel consumption (e.g., gallons/mile) for the urban and Recognizing the challenge and complexity of its work, the highway schedule converted into fuel economy (e.g., miles/ committee organized its members in working groups focused gallons) to compare to the CAFE standards. Therefore, from on the individual tasks outlined in its charge. There were four a regulatory viewpoint, fuel consumption is also the funda- such groups, each with its own leader responsible for task mental measure (or “metric”). work, coordination, and scheduling under the umbrella of the Because trucks and buses are designed to carry pay- broader committee. loads, and the loaded weight of a truck may be more than Given the constrained time and legislative deadline it double the empty weight, the way to represent an appropriate faced, the committee used specialized consultants to execute attribute-based fuel consumption metric is to normalize the various portions of the study directed by a committee work- fuel consumption to the payload the vehicle hauls. As noted ing group. The consultants and their assignments were: previously, this metric is called load-specific fuel consump- tion (LSFC) and is measured in gallons of fuel per payload

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 INTRODUCTION • Detroit Diesel Corp. TIAX, LLC—Deeloping Detailed Forecasts of Fuel Con- • Eaton Corp. sumption Reducing Technologies: • Tank and Automotive Research, Development and • Supported the committee’s evaluation of medium- and Engineering Center (TARDEC), U.S. Army heavy-duty vehicle technologies by researching the • PACCAR, Inc. technologies and their costs through intensive inter- • Volvo Trucks North America views of manufacturers, fleet owners and, others to • Cummins, Inc. produce a detailed matrix relating technologies and • Great Dane Trailers (Great Dane LLC) vehicle types over time. • Walmart • Developed a detailed matrix of fuel-saving technolo- • Transportation Research Center, Inc. gies, their fuel consumption benefits, and their costs. • National Highway Transportation Safety Administra- • Focused on a 10-year time frame. tion (NHTSA), Washington, D.C. • Arranged specific site visits for the committee. All of these consultants and industry partners provided in- Argonne National Laboratory—Modeling and Simulation: valuable assistance to the committee in its efforts. • Provided quantitative data to support the committee in its task of establishing a report to support rulemaking on medium- and heavy-duty vehicle fuel consump- REPORT STRUCTURE tion. • Provided modeling and simulation analyses of tech- This report begins with a summary of the key findings nologies now and into the future for eight vehicle ap- and recommendations. Chapter 1, the introduction, lays the plications: pickup truck, van, delivery straight truck, factual background for the reader. Next, Chapter 2 provides bucket truck, combination tractor trailer, refuse hauler, vehicle fundamentals necessary for a thorough understand- urban bus, and intercity highway bus. ing of the topics addressed in the report. Chapter 3 surveys the current U.S., European, and Asian approaches to fuel economy and regulations. Chapter 4 reviews and assesses Cambridge Systematics and ERG: • Examined possible consequences or side effects of fuel power train technologies for reducing load-specific fuel con- economy standards or of technologies to improve the sumption. Chapter 5 covers vehicle technologies for reducing fuel efficiency of medium- and heavy-duty vehicles. load-specific fuel consumption. The direct and indirect costs • Examined alternative approaches to improving fuel and benefits of integrating fuel economy technologies me- efficiency. dium- and heavy-duty vehicles are addressed in Chapter 6. Chapter 7 discusses alternative approaches to be considered The four consultants’ reports are available in the National for reducing the fuel consumption of such vehicles. Chapter Academies Public Access File associated with this study. 8 discusses approaches to measurement and regulation of In addition, the committee distributed a questionnaire to fuel consumption. aerodynamics technology stakeholders in the private and academic sectors from which it received useful input. The BIBLIOGRAPHY committee’s efforts were also aided by several industry orga- DOC (U.S. Department of Commerce), Census Bureau. 2005. 2002 Eco- nizations that hosted site visits providing relevant informa- nomic Census, Industry Product Analysis. Washington, D.C. March. tion, which proved especially helpful for the work of TIAX. DOE, EIA (U.S. Department of Energy, Energy Information Administra - They included the following: tion). 2009a. Annual Energy Review 2008. Report No. DOE/EIA- 0384(2008). Washington, D.C. • The University of Michigan Transportation Research DOE, EIA. 2009b. Annual Energy Outlook 2009. Report No. DOE/EIA- DOE/EIA-0383(2009). Washington, D.C. March. Institute (UMTRI), Ann Arbor DOE, EIA. 2009c. Annual Energy Outlook 2010 (Preliminary). Washington, • Ford Motor Co. D.C. December. • Azure Dynamics Corp. Davis, S., S. Diegel, and R.G. Boundy. 2009. Transportation Energy Data • Arvin Meritor, Inc. Book, Edition 28, Table 5.7. Knoxville, Tenn.: U.S. Department of • Navistar International Corp. Energy, Energy Efficiency and Renewable Energy. Report No. ORNL- 6984. • ISE Corp. Federal Highway Administration, Highway Statistics Summary to 1995, • Allison Transmission, Inc. Table VM-201A, and Highway Statistics (annual releases), Table VM-1. • Peterbilt Trucks (PACCAR Co.) Washington D.C. • Auto Research Center, Inc., Indianapolis, Ind. ICCT (Northeast States Center for a Clean Air Future/International Council • U.S. Environmental Protection Agency (EPA), Ann on Clean Transportation). 2009. Setting the Stage for Regulation of Heavy-Duty Vehicle Fuel Economy and GHG Emissions: Issues and Arbor, Mich. Opportunities. February. • Southwest Research Institute (SwRI), San Antonio, NRC (National Research Council). 2008. Review of the 21st Century Truck Tex. Partnership. Washington, D.C.: The National Academies Press.

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