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2 Vehicle Fundamentals, Fuel Consumption, and Emissions
Pages 17-40

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From page 17...
... Table 2-4 identifies the 10 cities in North America registrations, fuel economy, fuel consumption, mileage, and with the largest transit bus fleets. Table 2-5 gives information other information across the various vehicle classes.
From page 18...
... - 2400 to 250- 10-20 7,781,000 135 25-33 15 69.0 250-750 74.979 6-25 1,682 6000 5000 1,000 1t Minivans, Small SUVs, Small (4000) - 3200 to 250- 8-33 6,148,000 70 20-25 17 58.8 300-1k 37.400 6-25 813 Pick-Ups 6000 4500 1,500 2a Large SUVs, Standard Pick-Ups 6001- 4500 to 250- 6-40 2,030,000 23 20-21 26 38.5 500-1.2k 18.000 10-25 305 8500 6000 2,500 2b Large Pick-Up, Utility Van, Multi- 8501- 5,000- 3,700 60 545,000 6.2 10-15 26 38.5 1.5k-2.7k 5.500 15-40 93 Purpose, Mini-Bus, Step Van 10,000 6,300 3 Utility Van, Multi-Purpose, Mini- 10,001- 7,650- 5,250 60 137,000 0.69 8-13 30 33.3 2.5k-3.8k 1.462 20-50 12 Bus, Step Van 14,000 8,750 4 City Delivery, Parcel Delivery, 14,001- 7,650- 7,250 80 48,000 0.29 7-12 42 23.8 2.9k-5k 0.533 20-60 4 Large Walk-in, Bucket, Landscaping 16,000 8,750 5 City Delivery, Parcel Delivery, 16,001- 9,500- 8,700 80 41,000 0.17 6-12 39 25.6 3.3k-5k 0.258 20-60 2 Large Walk-in, Bucket 19,500 10,800 6 City Delivery, School Bus, Large 19,501- 11,500- 11,500 80 65,000 1.71 5-12 49 20.4 5k-7k 6.020 25-75 41 Walk-in, Bucket 26,000 14,500 7 City Bus, Furniture, Refrigerated, 26,001- 11,500- 18,500 125 82,411 0.18 4-8 55 18.2 6k-8k 1.926 75-200 9 Refuse, Fuel Tanker, Dump,Tow, 33,000 14,500 Concrete,Fire Engine,Tractor-Trailer 8a Dump, Refuse, Concrete, Furniture, 33,001- 20,000- 20,000 100-150 45,600 0.43 2.5-6 115 8.7 10k-13k 3,509 25-75 12 City Bus, Tow, Fire Engine (straight 80,000 34,000 to trucks)
From page 19...
... equipment builder. The chassis and power train come from • Major manufacturers for Class 8 vehicles have not one of the major vehicle original equipment manufactur varied over the past 5 years with one exception -- the ers (OEMs)
From page 20...
... program, trucker. At the other end are large fleets with thousands of which required automobile manufacturers to increase the trucks supported by sophisticated logistics and maintenance average fuel economy of vehicles sold in the United States systems.
From page 21...
... 16. TABLE 2-4 Top 10 Transit Bus Fleets in the United States and Canada SOURCE: Courtesy of Metro Magazine (2009)
From page 22...
... • Fuel consumption is the inverse measure -- the amount of fuel consumed in driving a given distance -- and is • Fuel economy is a measure of how far a vehicle will measured in units such as gallons per 100 miles or li ters per kilometer. Fuel consumption is a fundamental engineering measure and is useful because it is related 1A dynamometer is a machine used to simulate the forces on a drive directly to the goal of decreasing the amount of fuel train to test pollutant emissions, fuel consumption, and other operating required to travel a given distance.
From page 23...
... The data on the graph show the resulting decrease age is calculated using the fuel consumption of individual in fuel consumption per 100 miles and the total fuel saved in driving 10,000 miles. The dramatic decrease in the impact ∑ n Nn of increasing fuel economy by 100 percent for a high fuel average weighted CAFE = 1 2 Harmonic 1 1 ∑ 1 N n FE + … + N n FE n economy vehicle is most visible in the case of increasing the 1 n fuel economy from 40 to 80 mpg, where the total fuel saved where Nn = number of vehicles in class n, FEn = fuel economy of class n in driving 10,000 miles is only 125 gallons, compared to vehicles and n = number of separate classes of vehicles.
From page 24...
... termines the yearly fuel savings in going from a given fuel Because of the nonlinear relationship in Figure 2-2, economy vehicle to a higher fuel economy vehicle: consumers of light-duty vehicles have been shown to have difficulty using fuel economy as a measure of fuel efficiency Yearly Fuel Savings = in judging the benefits of replacing the most inefficient ve hicles. Larrick and Soll (2008)
From page 25...
... This is the typical way 1 these vehicles operate, although different light-duty vehicles Load-Specific Fuel Economy (LSFE)
From page 26...
... SOURCE: Jeffrey Seger, Cummins, Inc., personal communication, June 6, 2009. bitmap FIGURE 2-5 Fuel consumption versus payload SOURCE: Jeffrey Seger, Cummins, Inc., personal communication, June 6, 2009.
From page 27...
... Further, it is important that any standard for fuel effi Line Haul Urban Delivery ciency be based on LSFC, since it focuses on reducing the Vehicle weight empty (lb) 33,500 7,500 fuel consumed by medium-and heavy-duty vehicles sold Engine power (hp)
From page 28...
... Since hybrid vehicles The Recommended Practices of the Society of Automohave at least two sources of power during part of their duty tive Engineers (SAE) present details of road testing and cycle, the engine power demand model must be adjusted to of chassis dynamometer methods to determine hybrid and account for the flow of power to or from other sources dur conventional vehicle fuel economy.5 ing operation.
From page 29...
... It measures ated in tandem with a test vehicle to provide reference fuel fuel consumption and requires that average speed be conconsumption data. This procedure has become the de facto trolled to 55 to 62 mph preferred, 65 mph maximum (EPA, test for both carrier and manufacturer fuel economy evalua- 2009)
From page 30...
... The computer Validation of Test Results codes/procedures often embody unique individualities of their various developers, and no single practice has emerged The SAE has tasked its Truck and Bus Aerodynamic and as a standard. Fuel Economy Committee to bring the various current SAE Manufacturers are increasingly using this tool to provide procedures and practices into the needs of the 21st century, details of aero effects helpful to differentiate multiple de reflective of prevailing engineering and scientific data analysign features even before building models for wind tunnel sis to facilitate robust validation.
From page 31...
... schedule used in the E-55/59 California truck emissions inventory program. The idle, creep, transient, TEST-CYCLE DEVELOPMENT AND CHARACTERISTICS cruise, and high-speed cruise modes represent progressively higher average speeds of operation (Gautam et al., 2002; Development of Test Cycles Clark et al., 2004)
From page 32...
... Very Application of a Cycle low speed cycles have high idle content, and idle content On a chassis dynamometer, the vehicle speed provides diminishes. In the same way, values such as "stops per unit for unambiguous wind drag and rolling resistance terms distance," average instantaneous acceleration or deceleraprovided that the frontal area, drag coefficient, air density, tion, and coefficient of variance of speed become smaller as vehicle mass, gravitational acceleration, and tire rolling average speed rises.
From page 33...
... . Filtered Filtered Filtered The effect of drive cycle is also well documented for Creep Transient Cruise light-duty vehicles and is known to affect emissions in ad Mode of Mode of of Test-D dition to fuel economy (Nam, 2009; Wayne et al., 2008)
From page 34...
... Figure 2-13 shows this way the minimum occurs at low speeds for automobiles data for a number of cycles used in transit bus testing and and at high speed for heavily loaded large trucks. Figure 2-12 shows a correlation between the standard deviation of speed shows the results of Argonne National Laboratory's PSAT and the average speed.
From page 35...
... In addition, some power trains are less correlation between the nature of activity and the average efficient under transient operation than under steady operaspeed of activity is provided elsewhere in a plot for data from tion. If distance-specific fuel consumption is plotted against automobiles.12 average speed, a curve is produced that is concave upward, The effect of the increased transient behavior at low speeds with high values near zero speed, a minimum at midspeed, and rising values at very high speeds when aerodynamic forces start to dominate.
From page 36...
... FIGURE 2-15 Curves based 2-15 Curves based on chassis dynamometer for fuel eco.eps Figure on chassis dynamometer for fuel economy versus average speed for conventional and hybrid buses. SOURCE: Wayne et al.
From page 37...
... 13 DOT/NHTSA, "Corporate Average Fuel Economy Compliance and At the same time, a hybrid might allow the engine to operEffects Modeling System Documentation," DOT HS 811 112, April 2009. 14 EPA, "The MOVES Approach to Model Emission Model," CRC On ate in modes where emissions are lower than they would be Road Vehicle Emission Workshop, March 2004.
From page 38...
... These built models vehicle development process. As such, one can envision that along with some simulation tools can lead to rapid proto some of the same techniques used to accelerate the introductyping, virtual functional verification, software testing, and tion of new technologies on the market could also be part of validation.
From page 39...
... 2009. Setting the Stage for Regulation Future standards might require different values to accurately of Heavy-Duty Vehicle Fuel Economy and GHG Emissions: Issues reflect the applications of the various vehicle classes (e.g., and Opportunities.
From page 40...
... Research Council's 14th On-Road Vehicle Emission Workshop, San SAE J2711 Recommended Practice for Measuring Fuel Economy and Diego, Calif., March 29-31. Available at http://www.epa.gov/otaq/ Emissions of Hybrid-Electric and Conventional Heavy-Duty Vehicles.


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