## Assessment of Fuel Economy Technologiesfor Medium- and HeavyDuty Vehicles

Final Report

Report to National Academy of Sciences 500 Fifth Street NW Washington, DC 20001

November 19, 2009

Contract Number: DEPS-P290355

Prepared by Matthew A. Kromer Wendy W. Bockholt Michael D. Jackson

TIAX LLC 20813 Stevens Creek Blvd. Suite 250 Cupertino, California 95014-2192 Tel 408-517-1550 Fax 408-517-1551

TIAX Case D0506iii Table of Contents

Abbreviations.................................................................................................................. ............... xi Acknowledgement ................................................................................................................ ....... xiii Executive Summary.............................................................................................................. ...........1
1. Introduction................................................................................................................ ...... 1-1 2. Vehicle and Duty Cy cle Descriptions.............................................................................. 2-1
2.1 Class 8 Tractor Trailer ......................................................................................... 2-2
2.2 Class 8 Refuse Hauler.......................................................................................... 2-4
2.3 Class 3-6 Box and Bucket Trucks........................................................................ 2-4
2.4 Urban Transit Bus................................................................................................ 2-5
2.5 Motor Coach ........................................................................................................ 2-6 2.6 Class 2b Pickups and Vans .................................................................................. 2-7 3. Technology Matrix Description....................................................................................... 3-1 4. Fuel Saving Technologies................................................................................................ 4-1 4.1 Engine and Emissions Technologies ................................................................... 4-1
4.1.1 Overview.............................................................................................................. 4-1 4.1.2 Diesel Engine Technologies ................................................................................ 4-2 4.1.3 Diesel Engine Technology Descriptions.............................................................. 4-8 4.1.4 Diesel Engine Technology Packages................................................................. 4-20 4.1.5 Gasoline Engine Technologies .......................................................................... 4-30 4.1.6 Class 2b Engine Packages.................................................................................. 4-33 4.2 Aerodynamics .................................................................................................... 4-34
4.2.1 Overview............................................................................................................ 4-34
4.2.2 Class 8 Tractor Trailers...................................................................................... 4-37 4.2.3 Straight Box Truck Aero.................................................................................... 4-51
4.2.4 Motor Coach ...................................................................................................... 4-52 4.2.5 Class 2b Pickups and Vans ................................................................................ 4-53
4.3 Tires and Wheels................................................................................................ 4-54
4.3.1 Overview............................................................................................................ 4-54 4.3.2 Technologies for Reduci ng Rolling Resistance................................................. 4-55 4.3.3 Application of Tire and Wheel Technol ogy to Different Vehicle Classes ........ 4-58 4.4 Weight Reduction .............................................................................................. 4-61
4.4.1 Overview............................................................................................................ 4-61iv 4.4.2 Class 8 Tractor Trailer ....................................................................................... 4-62
4.4.3 Transit Bus......................................................................................................... 4-64
4.4.4 Motor Coach ...................................................................................................... 4-65 4.4.5 Class 3-6 Straight Box and Bucket Trucks........................................................ 4-66
4.4.6 Refuse Hauler..................................................................................................... 4-66 4.4.7 Class 2b Pickups and Vans ................................................................................ 4-67 4.4.8 Weight Increases................................................................................................ 4-67
4.5 Transmission and Driveline ............................................................................... 4-68 4.5.1 Tractor Trailer (On-highwa y, manual transmission) ......................................... 4-68 4.5.2 Class 3-6 box and bucket, refuse ha ulers, and urban transit buses.................... 4-70 4.5.3 Motor Coach (On-Highway, automatic transmission)....................................... 4-72 4.5.4 Class 2b Pickups and Vans ................................................................................ 4-73 4.6 Hybrid Technologies.......................................................................................... 4-74
4.6.1 Overview............................................................................................................ 4-74 4.6.2 Overview of Hybrid System Architectures........................................................ 4-76 4.6.3 Cross-Cutting Issues and Future Outlook.......................................................... 4-79 4.6.4 Summary — Hybrid Applications ..................................................................... 4-81
4.7 Idle Reduction.................................................................................................... 4-89 4.7.1 Automatic Shut-Down/Start-Up Systems.......................................................... 4-90 4.7.2 Battery-Powered ................................................................................................ 4-90 4.7.3 Fuel-Operated Heaters ....................................................................................... 4-92 4.7.4 Auxiliary Power Units ....................................................................................... 4-92 4.7.5 Truck Stop Electrification.................................................................................. 4-94 4.7.6 Idle Reduction System Comparison................................................................... 4-94 4.8 Driver Management and Coaching .................................................................... 4-96
4.8.1 Overview............................................................................................................ 4-96 4.8.2 Description of Management and Coaching Strategies....................................... 4-97 4.8.3 Summary............................................................................................................ 4-99 5. Packages.................................................................................................................... ....... 5-1 5.1 Capital Costs, Benefits, and Capital Cost Per Percent Reduction (CCPPR) ....... 5-1 5.2 Payback Analysis............................................................................................... 5-11 Appendix A. References ........................................................................................................ .... A-1v List of Tables

Table ES-1. Approaches for Reducing Fuel Consumed in Medium and Heavy-Duty Trucking Applications.................................................................................... ES-2 Table ES-2. 2008 Vehicle Technology and Duty Cycle Baseline ......................................ES-3 Table ES-3. Fuel consumption reducti on, capital cost, and CCPPR - 2015 to 2020 vehicle technology ..........................................................................................ES-6 Table ES-4. Simple Payback Analysis for Tractor Trailer, Transit Bus, Refuse Hauler, and Class 3- 6 Box Trucks ..................................................................ES-8
Table 1-1. NAS Committee on Medium- and He avy-Duty Fuel Economy Members .......1-2 Table 1-2. Site Visits Performed by Co mmittee Members, NAS, and TIAX staff ............1-4
Table 2-1. DOT and EPA truck weight classifications.......................................................2-1 Table 2-2. Fuel consumption by vehicle weight class and type [VIUS 2004] ................... 2-2 Table 2-3. Energy balance for a fully loaded Class 8 vehicle operating on a level road at 65 miles per hour for 1 hour ..................................................................2-3 Table 3-1. Technology matrix table descriptions ...............................................................3-1 Table 3-2. 11 to 15L engi ne technology matrix..................................................................3-5 Table 3-3. 6 to 9L engi ne technology matrix......................................................................3-7 Table 3-4. 5 to 8L gasoline engine technology matrix .......................................................3-9
Table 3-5. Tractor traile r technology matrix.....................................................................3-11
Table 3-6. Refuse hauler technology matrix.....................................................................3-17 Table 3-7. Transit bus technology matrix.........................................................................3-19
Table 3-8. Class 3-6 box and buc ket truck technology matrix .........................................3-21 Table 3-9. Class 2b pickup a nd van technology matrix....................................................3-23 Table 3-10. Motor coach technology matrix.......................................................................3-25 Table 4-1. Medium- and heavy-duty vehi cle technology matrix assumptions...................4-1
Table 4-2. Baseline characteristics for 2007 medium- and big-bore diesel engines ..........4-5 Table 4-3. 2008 and 2010 11 to 15L sample hea vy-duty diesel engine specifications ......4-6 Table 4-4. 2008 and 2010 6-9L heavy-duty diesel engine specifications........................... 4-7 Table 4-5. Baseline engine efficiency assumptions [Site Visits, DOE 2000, NHTSA 2009].................................................................................................................. 4-8 Table 4-6. Emissions strategies...........................................................................................4-9 Table 4-7. Strategies to reduce heat transfer and exhaust losses ......................................4-11 Table 4-8. Strategies to re duce gas exchange loss............................................................4-13vi Table 4-9. Friction redu ction strategies ............................................................................4-15
Table 4-10. Parasitic load reduction strategies ...................................................................4-16
Table 4-11. Waste heat r ecovery strategies ........................................................................ 4-16 Table 4-12. Technology Road Map fo r 11-15 L Diesel Engines........................................4-21 Table 4-13. Engine Technology road ma p for 6-9L diesel engines....................................4-22 Table 4-14. Engine technology package capital cost.......................................................... 4-23
Table 4-15. Overview of e ngine technology packages....................................................... 4-24 Table 4-16. 2010 engine technologies ................................................................................ 4-25 Table 4-17. 2013 engine technologies ................................................................................ 4-27 Table 4-18. 2015 engine technologies ................................................................................ 4-28 Table 4-19. 2016 to 2020 engine technologies ...................................................................4-29 Table 4-20. Gasoline engine technol ogy capital costs and benefits ...................................4-31 Table 4-21. Class 2b engine technology packages .............................................................4-33 Table 4-22. Impact of Highway Speed on Aerodynamic Improvement Potential..............4-35 Table 4-23. Comparison of aerodyna mic evaluation methodologies .................................4-36
Table 4-24. Class 8 tractor trai ler aerodynamic technologies.............................................4-37 Table 4-25. Summary of Aerodynamic Retr ofit Devices Literature Review ..................... 4-44 Table 4-26. Tractor trailer aerodynamic packages .............................................................4-50 Table 4-27. Straight box truc k aerodynamic technologies .................................................4-51 Table 4-28. Motor coach aerodynamic technologies..........................................................4-53 Table 4-29. Class 2b pickup and van aerodynamic technologies .......................................4-53
Table 4-30. Assumed tire ch aracteristics for class 8 tractor trailers ...................................4-57 Table 4-31. Tire pressure monitoring and inflation systems ..............................................4-58 Table 4-32. Rolling resistance scaling parameters .............................................................4-58
Table 4-33. Class 8 tractor traile r tire and wheel technologies...........................................4-59 Table 4-34. Motor coach tire and wheel technologies........................................................4-59
Table 4-35. Class 3-6 box and bucket truck tire and wheel technologies...........................4-60
Table 4-36. Transit bus tire and wheel technologies .......................................................... 4-60
Table 4-37. Refuse hauler ti re and wheel technologies ......................................................4-61 Table 4-38. Class 2b tire and wheel technologies...............................................................4-61 Table 4-39. Weight reduction capital cost and benefit for volume-constrained class 8 tractor trailers...................................................................................................4-64 Table 4-40. Weight reduction capital co st and benefit for transit buses.............................4-65 Table 4-41. Weight reduction capital co st and benefit for motor coaches .........................4-66vii Table 4-42. Weight reduction capital cost and benefit for class 3-6 box and bucket trucks ...............................................................................................................4-66 Table 4-43. Weight reduction capital co st and benefit for refuse haulers .........................4-67 Table 4-44. Weight reduction ca pital cost and benefits for class 2b pickups and vans......4-67 Table 4-45. Weight penalty for fuel savings and emissions control...................................4-68 Table 4-46. Driveline and transmission op tions for class 8 tr actor trailers .......................4-70 Table 4-47. Estimated capital cost of going from 6 to 8 speed automatic transmission.....4-72
Table 4-48. Driveline and tran smission strategies for refu se hauler, class 3-6 box and bucket trucks, and transit buses ....................................................................... 4-72
Table 4-49. Driveline and transmissi on strategies for motor coach ...................................4-73
Table 4-50. Driveline and transmission stra tegies for class 2b pickups and vans..............4-73 Table 4-51. Hybrid architectures ........................................................................................4-76 Table 4-52. Production-intent medium duty and heavy duty HEV systems, no ePTO ......4-81 Table 4-53. Hybrid technology capital costs and FC benefits for class 3-6 box trucks .....4-82 Table 4-54. Hybrid technology capital cost and FC benefits for class 3-6 bucket trucks ...............................................................................................................4-83 Table 4-55. Hybrid technology capital cost a nd FC benefits for refuse haulers.................4-84 Table 4-56. Hybrid technology capital cost a nd benefits for cla ss 8 tractor trailer hybrids a ............................................................................................................ 4-85 Table 4-57. Hybrid technology capital cost and benefits for transit buses.........................4-87 Table 4-58. Hybrid technology capital cost and benefits for motor coaches......................4-88 Table 4-59. Hybrid technology capital cost and benefits for class 2b pickups and vans.................................................................................................................. 4-89
Table 4-60. Automatic shut-down/ start-up systems comparison........................................4-90 Table 4-61. Battery-powered idle reduction systems comparison...................................... 4-91 Table 4-62. Fuel-operated heater comparison ....................................................................4-92
Table 4-63. Available auxiliar y power unit comparison ....................................................4-93 Table 4-64. Truck stop elect rification comparison.............................................................4-94 Table 4-65. Idle reduction systems comparison .................................................................4-95 Table 4-66. Driver management and coaching strategies –capital co sts and benefits......4-100 Table 4-67. Driver management and coaching strategies – approach ..............................4-100
Table 5-1. Tractor Trailer 2015- 2020 Technology Package............................................... 5-2 Table 5-2. Class 3-6 Box 2015-2020 Technology Package................................................5-3 Table 5-3. Class 3-6 Bucket 2015-2020 Technology Package ...........................................5-3
Table 5-4. Class 8 Refuse Haul er 2015-2020 Technology Package................................... 5-4viii Table 5-5. Transit Buses 2015- 2020 Technology Package ................................................ 5-5
Table 5-6. Motor Coaches 2015- 2020 Technology Package.............................................. 5-5 Table 5-7. Class 2b Pickups and Va ns 2015-2020 Technology Package ........................... 5-6 Table 5-8. Fuel consumption reducti on, capital cost, and CCPPR - 2013 to 2015 vehicle technology.............................................................................................5-7 Table 5-9. Fuel consumption reducti on, capital cost, and CCPPR - 2015 to 2020 vehicle technology.............................................................................................5-8 Table 5-10. Operational characteri stics for payback evaluation......................................... 5-12ix List of Figures

Figure ES-1. Examples of Vehicl e Applications Considered................................................ES-2 Figure ES-2. Comparison of 2015-2020 Fuel Savings Technology for Tractor Trailer (TT), Class 3-6 Box (Box), Class 3-6 Bucket (Bucket), Class 8 Refuse (Refuse), Transit Bus (Bus), Motor Coach (Coach), and Class 2b Pickups and Vans (2b) ...................................................................................................ES-4 Figure ES-3 Cost curves for 2015-2020 technolo gy packages. The transit bus extends to $250,000 at a benefit of 50 percent....................................................................ES-7
Figure 2-1. Class 8 tractor trailer .........................................................................................2-3 Figure 2-2. Class 8 refuse hauler.......................................................................................... 2-4 Figure 2-3. Class 3-6 box or van truc k (left) and bucket truck (right)................................. 2-5 Figure 2-4. Transit Buses ..................................................................................................... 2 -6 Figure 2-5. Typical over-the-road motor coach ...................................................................2-7 Figure 2-6. Examples of class 2b vans and pickup trucks ........................................................... 2-7 Figure 4-1. 2007 diesel engine energy audit [Duggal 2009]................................................4-3 Figure 4-2. Past and possible future brake thermal efficiency improvements for large bore engines [Site Visits, Duggal 2009, Cummins 2009a] ...............................4-4 Figure 4-3. Detroit Diesel Mechanical tur bo-compound system [Detroit Diesel 2009a].............................................................................................................. 4-17 Figure 4-4. Electric turbo-compound design schematic [Kruiswyk 2005] ........................4-19 Figure 4-5. Influence of aerodynamic drag on vehicle power demand as a function of speed................................................................................................................4-34 Figure 4-6. Standard sleeper tracto r aero technologies [Kenworth 2008] .........................4-39 Figure 4-7. Prostar and LoneStar Tractors [Navistar.com]................................................4-40 Figure 4-8. Examples of trailer side skirts [Laydon 2009, Freight Wing 2009] ................4-42 Figure 4-9. Examples of traile r base treatments (boat tail on the left, structural base flaps on the right) [Aerovolution 2009, AT Dynamics 2009] .........................4-42 Figure 4-10. Examples of trailer gap treatment s – front fairing (lef t), and splitter plate (right) [NoseCone 2009].................................................................................. 4-42 Figure 4-11. Survey of Trailer Aerodynamics (see Table 4-25 for detailed sourcing)........4-43 Figure 4-12. Example of a trim top roof fairing [Leuschen 2006]....................................... 4-45 Figure 4-13. Influence of rolling resist ance and aerodynamic drag on vehicle power demand as a function of speed.........................................................................4-54 Figure 4-14. Range of C RR for currently available tires [Bradley 2009]............................. 4-55x Figure 4-15. Tractor trailer weight reduction opportunities [Alcoa 2009] ..........................4-63 Figure 4-16. ALCOA estimates of weight-s aving opportunities fo r tractor trailers [Scheps 2008] .................................................................................................. 4-63 Figure 4-17. Weight savings realized for lightweight demonstration bus in China [Scheps 2008] .................................................................................................. 4-65 Figure 4-18. Parallel hybrid architecture [Coryell 2008].....................................................4-77 Figure 4-19. Parallel Hydraulic Hybrid (“La unch Assist”) Architect ure [Gotting 2007]....4-78 Figure 4-20. Lithium-ion vs. NiMH cost curves [Miller 2006] ...........................................4-79 Figure 4-21. Fuel economy benefits of 40-f oot hybrid transit buses compared to 40- foot diesel transit buses ...................................................................................4-86 Figure 4-22. Variance in driver performance [Cummins 2007]........................................... 4-96 Figure 5-1. Comparison of Fuel Savings T echnology for Tractor Trailer (TT), Class 3-6 Box (Box), Class 3-6 Bucket (B ucket), Class 8 Refuse (Refuse), Transit Bus (Bus), Motor Coach (Coach), and Class 2b Pickups and Vans (2b) ......................................................................................................... 5-10 Figure 5-2. Cost curves for 2013-2015 pack ages. The transit bus extends to $215,000 at a benefit of 40 percent .................................................................................5-10 Figure 5-3. Cost curves for 2015-2020 pack ages. The transit bus extends to $250,000 at a benefit of 50 percent .................................................................................5-11xi Abbreviations

ABA American Bus Association
APTA American Public Tr ansportation Administration BSFC Brake specific fuel consumption CCPPR Capital cost per percent reduction
C D Coefficient of aerodynamic drag
C RR Coefficient of tire rolling resistance
DD Detroit Diesel DOE United States Department of Energy
DOHC Dual overhead cam
DPF Diesel Particulate Filter
EGR Exhaust Gas Recirculation EPA United States Environmental Protection Agency FC Fuel consumption FE Fuel economy FI Fuel injection
Gal Gallon GDI Gasoline direct injection HCCI Homogeneous charge compression ignition HD Heavy Duty
HP Horse Power
HPh Horse Power Hour
ICCT International Center for Clean Transportation Kg Kilogram
kW Kilowatt
kWh Kilowatt hour
Lb Pound LB GDI Lean-burn gasoline direct inject MD Medium duty MPG Miles per gallon MPH Miles per hourxii NAS National Academy of Sciences
NESCCAF Northeast States Center for a Clean Air Future NHTSA National Highway Traffic Safety Administration NOx Oxides of nitrogen O&M Operations and maintenance OBD Onboard diagnostics
OHV Overhead valve
PM Particulate matter RPE Retail price equivalent
SwRI Southwest Research Institute SCR Selective catalytic reduction sGDI Stoichiometric gasoline direct injection SOHC Single overhead cam
TT Tractor trailer VG Variable geometry
VVA Variable valve actuation
VVL Variable valve lift VVT Variable valve timing Wt Weightxiii Acknowledgement

This report was prepared for the National Academ y of Sciences (NAS) as part of their prime contract with the National Highway Traffic Sa fety Administration (NHT SA) to assess fuel economy technologies for medium and heavy dut y vehicles. The National Research Council (NRC) Division on Engineering a nd Physical Sciences was res ponsible for this work and assigned the effort to the Board on Energy and E nvironmental Systems. The project identifier is BEES-J-08-A. The NAS project director wa s Mr. Duncan Brown and the TIAX principal investigator was Michael D. Jackson. Dr. Andrew Brown, Jr. chaired the NAS committee, initiated the project, and provide d valuable guidance to help dire ct and focus TIAX’s research. Mr. David Merrion was the NAS committee’s group leader on fuel economy technologies and assisted TIAX in developing site visits and reviewing and commenting on the results.
We would also like to thank all the companies that participate in the site visits. These companies took time out of their schedules to meet with TI AX staff, NAS staff, and committee members. Their willingness to host the site visits and to actively participate by prov iding their perspective on truck fuel economy technologies and futu re standards is greatly appreciated.ES-1 Executive Summary

The Energy Independence and Security Act of 2007 (EISA) requires that the National Highway Transportation and Safety Administration (NHTSA) conduct rulemaking to implement a commercial medium-duty (MD) and heavy-duty ( HD) on-highway vehicle and work truck fuel efficiency improvement program. To support this rulemaking activity, NHTSA engaged the National Academies of Sciences (NAS) to deve lop a report that evaluates MD and HD vehicle fuel economy. One of the NAS committee’s tasks requires the assessment of technologies and capital costs for improving MD and HD fuel economy.
TIAX was contracted to support the committee’ s evaluation of MD and HD technologies. The goal of this effort was to develop a matrix of fuel-saving technologies, their fuel consumption benefits, and their capital costs that could be implemented in medium- and heavy duty vehicles within a ten-year timeframe. To complete this work, TIAX, together with committee members, gathered data from a number of sources, includi ng site visits with industry and research laboratories; data presented to the committee during open sessions ; publicly available literature; prior TIAX technology and cost modeling; and disc ussions with experts from industry. In all, TIAX participated in 15 different site visits to truck OEMs, end-users, suppliers, research laboratories, and engi ne manufacturers.
The TIAX effort emphasized engine and vehicle technologies that sa ve fuel. Our effort did not address productivity improvements or operations and logistics improvements. Both productivity and operations/logistics improvement s can significantly reduce fuel consumed in many trucking applications. Table ES-1 summarizes wh at is included in the TIAX analysis.
TIAX focused on identifying fuel reduction tech nologies and strategies for seven different vehicle classifications: Class 8 Tractor Trailers, Class 3-6 Straight Box Trucks, Class 3-6 Utility (“Bucket”) Trucks, Class 8 Refu se Haulers, Urban Transit Buse s, Motor Coaches, and Class 2b Pickups Trucks and Vans. Figure ES-1 shows exampl es of the types of vehicles considered in this study.
Collectively, these vehicles, or other vehicles wi th similar mission profiles and characteristics, account for approximately 80 to 90 percent of th e fuel used in the medium- and heavy-duty, onroad truck sector. For each vehicle class, TIAX defined baseline vehicle characteristics that reflect industry-standard charac teristics for a 2008 to 2009 model year vehicle compliant with 2007 emissions regulations. TIAX also qualitatively characterized duty cycles for each vehicle class. Characteristics for each vehicle cl ass are summarized in Table ES-2.ES-2 Table ES-1 Approaches for Reducing Fuel Consumed in Medium and Heavy-Duty Trucking Applications

Approach TIAX analysis includes... TIAX analysis does not include... Technology Deploy fuel efficient technologies into the vehicle fleet • Identification of Technologies

• Estimate of fuel consumption benefit

• Cost estimates, retail price equivalent (RPE) • Breakdown of RPE

• Analysis of manufacturing processes

• Operations & Maintenance (O&M) Costs/Life Cycle Costing Productivity Increase the use of longer & heavier vehicles • Estimates of fuel consumption benefit

• Identification of enabling technologies • Cost analysis

• Infrastructure analysis

• Policy landscape
Operations & Logistics Optimize fleet management • On-vehicle optimization tools (e.g., driver training, telematic navigation, etc) • Off-vehicle fleet optimization tools

• Optimization of goods movement

2

Figure ES-1. Examples of Vehicle Applications Considered Tractor Trailer

Refuse Hauler Class 3-6 Box

Class 2b 40 ft Transit Motor Coach Class 3-6 BucketES-3 Table ES-2. 2008 Vehicle Technology and Duty Cycle Baseline

Truck Technology Duty Cycle

Class 8 Tractor Trailer • 11 to 15L diesel engine

• Smartway Tractor, 53’ Dry box van trailer; C D = 0.6

• Standard steel-rim dual tires

• 10 speed manual transmission w/overdrive

• 34,500 lbs unloaded

• 65,000 lb average; 80,000 lb max

• No idle reduction technology Line-Haul duty cycle:

• 55 to 60 MPH avg speed

• 120,000 miles per year

• 1,500 to 2,400 hrs/yr overnight idle

Class 3-6 Box Truck • 6 to 9L diesel engine

• No aerodynamic treatments

• 6 speed automatic transmission, PTO

• Standard steel-rim dual tires

• 16,500 lbs unloaded Regional or Pickup & Delivery duty cycle

• ~150 miles per day

• Average speed ~ 30 MPH

Class 3-6 Bucket Truck • 6 to 9L diesel engine

• No aerodynamic treatments

• 6 speed automatic transmission

• Standard steel-rim dual tires

• 16,500 lbs unloaded Utility Vehicle Duty Cycle:

• 6 hours idle per day

• ~30 to 40 miles per day

Refuse Hauler • 11 to 15L diesel engine

• 6 speed automatic transmission

• Standard steel-rim dual tires

• 35,000 lbs unloaded

• 80,000 lb GVW Refuse duty cycle:

• 150 ft between stops

• 500 to 800 stops per day

• Average speed ~ 12 MPH

• 50 to 60 miles per day 40-ft Transit Bus • 6 to 9L diesel

• l engine

• 6 speed automatic transmission

• Standard steel-rim dual tires

• 28,500 lbs unloaded Urban duty cycle:

• Average speed ~ 12 MPH

• Stops & starts

• 30 to 40 kW accessory load

Motor Coach • 11 to 15L diesel engine

• 6 speed automatic transmission

• Standard steel-rim dual tires

• 36,000 lbs unloaded High speed duty cycle:

• Average speed 45 to 50 MPH

• 56,000 miles per year

Class 2b pickups &
vans • 5 to 8L Gasoline engine

• 4 speed automatic transmission

• Standard truck tires

• 10,000 lbs unloaded High speed duty cycle:

• Mixed duty cycle

• Average speed ~ 30 MPH

• 15,000 miles per year

For each vehicle classification, fu el savings strategies were ca tegorized into one of several categories: engine efficiency improvement , aerodynamic drag reduction, tires and wheels, hybridization, transmission and dr iveline, weight reduction, driver management and coaching, and idle reduction 1 . In cases where capital cost data we re not available for a specific technology, TIAX used bottom-up cost methodologies to estimate costs. In cases where fuel efficiency or capital cost data were not availa ble for a particular vehicle class, TIAX applied data from other

1 In this context, idle reduction refers specifically to ov ernight hotel loads.ES-4 classes using appropriate scaling metrics such as vehicle weight, duty cycle characteristics, or engine torque. The results of this analysis of individual technologi es were compiled into a matrix of costs and benefits for each vehicle class.
From these estimates of individual technologies , packages were developed for each vehicle segments and for two time periods: 2013-2015 and 2015-2020. These technology packages are representative of what is possi ble in these time frames. Estimat es of fuel consumption savings, capital costs, and capital cost per percent fuel consumption reduction (CCPPR) were then made for each vehicle application based on the results of our site visits and existing literature. In general, these estimates are specific to the a pplications considered a nd as such should be a reasonable first cut of the overall fuel savings. Detailed drive cycle modeling will be necessary to refine and confirm these estimates.
Figure ES-2 shows the overall re sults of possible fuel consump tion (FC) benefits for each trucking application in th e 2015-2020 time frame. These results indicate for most applications it is possible to reduce fuel consumption by 50 percen t. The exceptions were the refuse hauler and motor coach applications. The major enabli ng technologies necessaryto achieve these reductions were hybridization, adva nced diesel engines, and aer odynamics. Hybridization is

0% 10% 20% 30% 40% 50% 60%

TT Box Bucket Refuse Bus Coach 2bFC Benefit Aero Engine Weight Tires & Wheels Transmission Hybrid Mgmt & Coaching

Figure ES-2. Comparison of 2015-2020 Fuel Savings Technology for Tractor Trailer (TT), Class 3-6 Box (Box), Class 3-6 Bucket (Bucket), Class 8 Refuse (Refuse), Transit Bus (Bus), Motor Coach (Coach), and Class 2b Pickups and Vans (2b)ES-5 particularly important in those applications with stop and go duty cycles characteristic of the Class 3-6 box and bucket, refuse, transit buses, and Class 2b applications . Hybrid drivetrains could include a variety of architectures from seri es to parallel and from electric to hydraulic systems. Diesel and gasoline engine advancements are also needed for all applications and will have to include continuing improvements to fuel injection systems, emission control, and air handling systems, in addition to commercializ ation of waste heat recovery systems and electrification of engine accesso ries. The third major technology improvement is improved total vehicle aerodynamics, especially in over-the-road applications lik e tractor trailers and motor coaches. Other technologies that will play a ro le in reducing fuel cons umption in all vehicle segments are low rolling resistance tires, impr oved transmissions, idle reduction technologies, weight reduction, and driver management and coaching Table ES-3 summarizes package results for 2015 -2020 technologies for the various vehicle segments. This table shows technology benefits, capital costs, and CCPPR (defined as the cost to reduce fuel consumption by 1 percent, or $/pe rcent fuel consumption benefit) for technologies that will be market-viable 2 between 2015 and 2020. The technologi es that are included vary by market segment, but broadly speaking, they in clude a hybrid system for urban vehicles and aerodynamic improvements coupled with first ge neration waste heat recovery on highway vehicles. All of the technologies include significant engine efficiency improvements as shown. The capital costs of the 2015-2020 technology p ackages range from $14,000 (Class 2b) to $250,000 (transit bus). However, the most of the applications lie in a narrow band from $40,000 to $85,000. Many of the technologies benefit from an ticipated reductions in the cost of hybrid vehicles during this timeframe. CCPPR es timates range from $250 to $5,000 per percent improvement, depending on vehicle class. For five of the seven vehicle classes, the benefits lie in a range from $500 to $1,700 per percent fuel consumption reduction.
Although the cumulative reductions and capital costs for vehicles classes are relatively similar, the likely pathway to achieve these benefits va ries considerably. For line-haul vehicles, wasteheat recovery and aerodynamics represent the largest opportunities, but high single-digit gains are possible in nearly every category. For urba n vehicles (box & bucket, buses, and refuse), hybridization provides the bulk of the benefit. In addition, engine optimization provides significant benefits to all vehi cle classes. To characterize th ese differences in the technology effectiveness of different strategies across vehicle segments, each strategy was ranked in order of CCPPR for each vehicle class. These data were th en used to generate cost-curves as shown in Figure ES-3.

2 “Market-viable” means that the technology will have matured to the point at which it could be widely deployed; it does not im ply that a particular technology offers attributes (such as rapid payback) that will lead to market adoption.ES-6 Table ES-3. Fuel consumption reduction, capital cost, and CCPPR - 2015 to 2020 vehicle technology

TT Box Bucket d Refuse Bus Coach 2b Fuel Consumption Reduction
Aero 11.5% 6%

— — — 8% 3% Engine 20% 14% 11.2% 14% 14% 20% 23% Weight 1.25% 4% 3.2% 1% 6.25% 1.05% 0.75%
Tire 11% 3% 2.4% 2.5% 1.5% 3% 2%
Transmission 7% 4% 3.2% 4% 4% 4.5% 7.5% Hybrid 10% 30% 40% 25% 35%

— 18% Mgmt 6%

— — — — — — Idle Reduction a

— — — — — — — Subtotal b 51.0% 49.4% 51.3% 40.2% 50.4% 32.5% 44.9% Added Wt (lb) c 2,030 1,100 1,050 1, 500 2,000 1,100 300 Adj. FC Total 50.5% 47.1% 49. 6% 38.4% 47.8% 32.0% 44.5% Capital Cost Aero $ 12,000 $ 3,250 $ - $ - $ - $ 4,500 $ 100 Engine $ 23,000 $ 13,000 $ 13,000 $ 14,800 $ 13,000 $ 23,000 $ 4,000 Weight $ 13,500 $ 4,770 $ 4,770 $ 3,000 $ 15,300 $ 6,000 $ 600 Tire $ 3,600 $ 300 $ 300 $ 300 $ 300 $ 450 $ 10 Transmission $ 5,800 $ 1,800 $ 1,800 $ 2,700 $ 1,800 $ 2,400 $ 1,000 Hybrid $ 25,000 $ 20,000 $ 30,000 $ 30,000 $ 220,000 $

— $ 9,000 Mgmt $ 1,700 $

—$

— $

— $

—$

— $

— Idle Reduction a $

— $

—$

— $

— $

— $

— $

— Total $ 84,600 $ 43,120 $ 49,870 $ 50,800 $ 250,400 $ 36,350 $ 14,710 CCPPR ($/Percent Fuel Consumption Benefit) Aero $ 1,043 $ 542 $ - $ - $ - $ 563 $ 33 Engine $ 1,150 $ 929 $ 929 $ 1,057 $ 929 $ 1,150 $ 174 Weight $ 10,800 $ 1,193 $ 1,193 $ 3,000 $ 2,448 $ 5,714 $ 800 Tire $ 327 $ 100 $ 100 $ 120 $ 200 $ 150 $ 5 Transmission $ 829 $ 450 $ 450 $ 675 $ 450 $ 533 $ 133 Hybrid $ 2,500 $ 667 $ 750 $ 1,200 $ 6,286 $

— $ 500 Mgmt $ 283 $

— $

— $

— $

— $

— $

— Idle Reduction a $

— $

— $

— $

— $

— $

— $

— All Packages $ 1,674 $ 915 $ 1006 $ 1,323 $ 5,232 $ 1,135 $ 331

a Overnight idle reduction is assumed to be implemented as part of the hybrid package b Does not include fuel consumption penalty associated with added weight of f uel savings technologies
c Added weight of fuel savings technologies d Assumes that 80% of fuel is used on road, and 20% is used at idleES-7 $- $10,000 $20,000 $30,000 $40,000 $50,000 $60,000 $70,000 $80,000 $90,000 $100,000

0% 10% 20% 30% 40% 50% 60%
% BenefitPackage Cost Tractor-Trailer Straight Box Bucket Refuse Bus Coach Class 2b

Figure ES-3. Cost curves for 2015-2020 technology packages. The transit bus extends to $250,000 at a benefit of 50 percent

A simple payback analysis was performed to estimate how viable the 2015-2020 packages are for each application. Table ES-4 shows operating characteristics for a ty pical tractor trailer, transit bus, refuse hauler, and Cl ass 3-6 box truck fleets. Key to this analysis was the assumed annual mileage and vehicle fuel economy. Fuel consumption for each application was determined with the results shown in Table ES-4. Then using the fuel savings potential shown in Table ES-1 for these four applications, fuel sa ved per year was estimated as was cost savings assuming diesel at $4 per gallon. As shown, excep t for transit buses the simple payback period is in the 2 to 4 year range. The transit bus numbers are reduce d to 2.3 years if Federal transit subsidies are included.
A more sophisticated life cycle costing will be required to adequately address the economic viability of the various fuel saving packages of each specific applicati on. However, preliminary results are favorable.ES-8 Table ES-4. Simple Payback Analysis for Tractor Trailer, Transit Bus, Refuse Hauler, and Class 3-6 Box Trucks

Characteristic Tractor Trailer Transit Bus Refuse Hauler Class 3-6 Box Annual Mileage (miles per year) 120,000 40,000 25,000 60,000 Average speed (miles per hour) 46.2 12 12 28.8 Driver work week (days per week) 6 5 5 5 Driver time (hours per week) 50 64 a 40 40 Fuel economy (miles per gallon) 6.5 3.5 3.3 8 Fuel consumption (gallons per year) 18,500 11,400 7,600 7,500 1% Fuel consumption savings (gal per yr) 185 114 76 75

Fuel cost savings for 1% reduction (@$4 per gallon diesel) $738 $457 $303 $300

Fuel cost savings for 1% reduction (at $3 per gallon diesel) $554 $343 $227 $225

Fuel use reduction (gal /year) 9,350 5,456 2,918 3,534 Fuel cost savings ($/year)@ $4/gal diesel $37,402 $21,825 $11,672 $14,136

Total added technology costs $84,600 $250,400 $50,800 $43,120 Payback Period (years) 2.3 11.5 a 4.4 3.1 Payback Period (months) 27.1 137.7 a 52.2 36.6

a With Federal subsidies technology costs are $52,400 and payback is 2.4 years or 28.8 months TIAX’s analysis shows that there is potential to achieve fuel consumption benefits of 40 to 50 percent across a broad subset of the medium- and heavy-duty vehicle fleet between 2015 and 2020, at costs that range from $40,000 to $90,000. Th e technologies used to achieve these benefits vary by segment: on urban vehicles, bene fits are largely driven by hybridization, while on-highway vehicles achieve be nefits through waste-heat r ecovery and aerodynamics. We speculate that some, but not all, of these fuel consumption benefits wi ll be achieved without regulation. A commonly cited rule of thumb is that line-haul tractor trailer fleets will pay $900 for 1 percent of efficiency improvement. Our analysis shows that 30 percent efficiency improvement can be achieved at a CCPPR of $640 per percent, while 50 percent efficiency improvement is achieved at a CCPPR of $1,700 pe r percent. In other vehicle segments, which have lower mileage, fuel efficiency is commonly valued at $250 per percent. In these segments, adoption is likely to be much lower. We project that in se veral segments, 50 percent fuel efficiency can be achieved at a CCPPR of $500 to $900 per percent.
It needs to be emphasized that our package resu lts are very dependent on the vehicle’s duty cycle and as such should be viewed as averages for e ach truck segment. Further, although the data for this analysis were obtained for the specific truck segments and, in general, for typical duty cycles for these segments, detailed vehicle stimulati on modeling was not done to establish the fuelES-9 consumption benefit of combined fuel savings te chnologies for each duty cycle. Follow up work is needed to confirm not only th e individual estimated benefits but also the packaged benefits.
Finally, the results of our data collection effort indicate two additional observations:

1. Technology is being developed today that co uld eliminate all idling from heavy-duty applications. This will requi re hybrid technologies and energy storage systems. These systems are anticipated to be comm ercialized in the next 10 years.

2. A national maximum speed limit could be set, and all new trucks could have this speed governed. This would unify at least one of the many truck specifications and would significantly reduce fuel use.1-1 1. Introduction

Congress requested the Department of Transportation to execute an agreement with the National Academy of Sciences (NAS) to develop a repor t evaluating medium-duty and heavy-duty truck fuel economy standards. 3 In response to this request, the National Academy of Sciences convened a committee with expertise in a broa d spectrum of areas including: compression ignition engine technology, fuels, emission cont rol technologies, vehicle systems engineering, R&D management, truck operations and management, design and manufacturing, commercialization of new technology, safety, fuel economy standards and policy, testing procedures, and transportation policy.
This committee is addressing a series of tasks wi th an ultimate goal of preparing a report with conclusions and recommendations for fuel ec onomy standards of me dium- and heavy-duty vehicles. The committee is tasked to:

• Consider appropriate approach es to measure fuel economy for medium- and heavy-duty vehicles that would be re quired for setting standards;

• Assess current and potential tec hnologies and estimate improvements in fuel economy for medium-duty and heavy-duty truc ks that might be achieved;

• Address how the technologies identified may be used practically to improve mediumduty and heavy-duty truck fuel economy;

• Address how such technologies may be practic ally integrated into the medium-duty and heavy-duty truck manufacturing process;

• Assess 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 Energy Independence and Security Act of 2007;

• Discuss the pros and cons of approaches to improve the fuel efficiency of moving goods as opposed to setting vehicle fuel economy standards; and,

• Identify the potential capital costs and othe r impacts on the operation of medium-duty and heavy-duty trucks. Members of the medium- and heavy-duty committ ee are shown in Table 1-1 and include current and prior industry leaders, academics, and members of national labs. This committee, as part of its approach to identify current and potential fu el economy technologies, d ecided to reach out to the trucking industry to gather in formation on these techno logies, their benefits, and their costs. Site visits to truck manufacturers, engine manuf acturers, and hybrid suppliers were planned to gather information on current as well as future technologies.

3 Energy Independence and Security Act of 2007 (H.R. 6), Section 1081-2 Table 1-1. NAS Committee on Medium- and Heavy-Duty Fuel Economy Members

Chair
Dr. Andrew Brown, Jr. (NAE) a Exec. Director & Chief Technologist Delphi Corporation

Members Dr. Dennis Assanis (NAE) a Jon R. & Berverly Holt Professor of Engineering University of Michigan
Dr. Roger Bezdek President Management Information Services, Inc. Oakton, Virginia Dr. Nigel Clark Prof. & Director Center for Alternative Fuels, Engines & Emissions West Virginia University

Mr. Thomas Corsi Director, Supply Chain Mgmt Center, Logistics, Business & Public Policy University of Maryland

Mr. Duke Drinkard VP, Maintenance (Retired) Southeastern Freight Lines Lexington, SC 29073

Dr. David Foster Professor of Mechanical Engineering University of Wisconsin
Dr. Roger Fruechte Director, Electrical & Contro ls Integration Lab (Retired) General Motors R&D

Dr. Ronald Graves Director, Fuels, Engines & Emissions Research Center Oak Ridge National Laboratory Mr. Garrick Hu Consultant West Bloomfield, MI

Dr. John H. Johnson Presidential Professor Michigan Tech University Houghton, Michigan
Mr. Drew Kodjak Executive Director International Council on Clean Transportation Washington, DC

Mr. David Merrion Exec. VP, Detroit Diesel (Retired) Brighton, Michigan

Mr. Tom Reinhart Program Manager, Engine Design & Development Southwest Research Institute
Mr. Aymeric Rousseau Program Manager Argonne National Laboratory Dr. Charles Salter Exec. Director, Engine Development (Retired) Mack Trucks / Volvo Powertrain Chambersburg, Pennsylvania
Dr. James Winebrake Chair, Dept. of Science, Technology & Public Policy Rochester Institute of Technology

Mr. John Woodrooffe Head, Transportation Safety Analysis University of Michigan Transportation Institute

Dr. Martin Zimmerman Clinical Professor of Business Administration University of Michigan

a Member National Academy of Engineers

TIAX LLC was asked to assist the committee in arranging and attending site visits and to develop a report summarizing current and future fuel economy technologies for Class 2b through Class 8 trucks. Our scope was to identify, for each truck class and applica tion, technologies that could improve fuel economy, their fuel consump tion benefits, and their costs. TIAX was also asked to gather public information on technologie s to improve truck fuel economy that could be used by the committee in its report. Finally, we were tasked to document our results in a report to the committee and NAS.1-3 Table 1-2 shows the site visits that were planned by TIAX and includes the committee members who attended these visits, as well as NAS st aff (Jim Zucchetto, Jason Ortego, Joe Morris, Duncan Brown), NTHSA staff (Mary Versailles , Ryan Harrington) and TIAX staff (Michael Jackson, Matt Kromer, Steven Lasher, Ray Schubert).
For each site visit, a presentation was developed that outlined Congress’ request, members of the committee, and technical information on fuel econo my technologies. Most of the data on fuel economy technologies were initiall y obtained from the literature but were refined as further information was obtained from the site visits. A total of 15 site visits were performed as shown in. In addition, TIAX attended the following committee meetings: April 6-7, 2009 in Detroit, MI; June 18-19, 2009 in Ann Arbor, MI; August 6-7, 2009 in San Antonio, TX. A number of companies presented at these meetings, and inform ation provided in their presentations was also included in our data gathering effort.

TIAX also attended the UMTRI International Co nference on Efficient, Safe, and Sustainable Truck Transportation held at the University of Michigan on June 16 and 17, 2009, and TIAX staff participated in site visits to the US EPA and UMTRI facilities in Ann Arbor on June 19, 2009. Again, data collected during these meetings a nd visits were included in our data collection effort.
This report documents the work performed to da te on identifying fuel economy technologies, and their FC benefit and capital cost s by truck class and use. Esti mates are based on a survey of publicly available studies and repor ts, presentations to the committ ee, and discussions during site visits with medium- and heavy-duty truck manufact urers, suppliers, and e nd-users. Due to the sensitive nature of information shared during the site visits w ith industry representatives, data gathered is cited as “site visits”.
Section 2 provides an overview and de scription of the classe s of trucks investigated in this effort. This overview is followed in Section 3 by summary matrices of fuel economy technologies for each vehicle class. Section 4 provides additi onal description of the technologies and our assumptions regarding interpre tation of the various inputs co llected and received. Finally, Section 5 presents possible technology packages for each vehicle clas s and application and estimates aggregate fuel consumption benefits an d capital costs. This section also includes a simple payback analysis.1-4 Table 1-2. Site Visits Performed by Committee Members, NAS, and TIAX staff

Date Company Visited Location Products Committee Members
April 8, 2009 Ford Motor Company Dearborn, MI Truck OE Class 2b-7 Dave Merrion, Chuck Salter, Drew Kodjak, Tom Reinhart, Jamie Winebrake, Marty Zimmerman, Jim Zucchetto, Jason Ortego, Michael Jackson April 8, 2009 Daimler Trucks North America, Detroit Diesel Detroit, MI Truck OE Class 4-8 Dave Merrion, Chuck Salter, Drew Kodjak, Tom Reinhart, Jamie Winebrake, Marty Zimmerman, Jim Zucchetto, Jason Ortego, Michael Jackson April 8, 2009 Azure Dynamics Oak Park, MI Tier 1 Hybrid System Supplier John Johnson, Roger Fruechte, Dennis Assanis, Nigel Clark, Duke Drinkard, Joe Morris, Ryan Harrington, Stephen Lasher April 8, 2009 Eaton Southfield, MI Tier 1 Hybrid System Supplier Andy Brown, Garrick Hu, Aymeric Rousseau, Dennis Assanis, John Woodrooffe, David Foster, Ron Graves, Duncan Brown, Mary Versailles, Matt Kromer April 8, 2009 Arvin Meritor Troy, MI Tier 1 Heavy Duty Component and Hybrid Supplier Andy Brown, Garrick Hu, Aymeric Rousseau, Dennis Assanis, John Woodrooffe, David Foster, Ron Graves, Duncan Brown, Mary Versailles, Matt Kromer

April 8, 2009 TARDEC Warren, MI End-user and Army Vehicle R&D John Johnson, Roger Fruechte, Dennis Assanis, Nigel Clark, Duke Drinkard, Joe Morris, Ryan Harrington, Stephen Lasher April 9, 2009 Navistar Fort Wayne, IN Truck OE Class 3-8 Andy Brown, Tom Reinhart, Chuck Salter, Ryan Harrington, Mike Jackson, Matt Kromer May 4, 2009 PACCAR Mount Vernon, WA Truck OE Class 3-8 Duncan Brown, Andrew Brown, David Merrion, Michael Jackson, Raymond Schubert May 7, 2009 ISE Corporation Poway, CA Tier 1 Hybrid and Fuel Cell Drive System Supplier Michael Jackson, Raymond Schubert Andrew Brown, Jr. (by phone), Dave Merrion (by phone)

May 13, 2009 Volvo Trucks NA Greensboro, NC Truck OE Class 6-8 Chuck Salter, Ron Graves, Duke Drinkard, Roger Fruechte, Duncan Brown, Michael Jackson, Matt Kromer May 14, 2009 Allison Transmissions Indianapolis, IN Tier 1 Transmission and Hybrid Supplier Duncan Brown, Michael Jackson, Matt Kromer, Dave Merrion, Tom Reinhart

May 15, 2009 Cummins Engine Company Columbus, IN Medium, Heavy Duty Engine Supplier Andy Brown, Jr, Dave Merrion, Chuck Salter, Tom Reinhardt, Ron Graves, Duncan Brown, Michael Jackson, Matt Kromer

July 22, 2009 Peterbilt Trucks, Great Dane Trailers, Wal-Mart Denton, TX Truck OE, Trailer OE, Regional Truck Hauler Andy Brown, Jr, Dave Merrion, Chuck Salter, Roger Fruechte, Ron Graves, Duncan Brown, Michael Jackson, Matt Kromer

August 11, 2009 Auto Research Center Indianapolis, IN Aerodynamic Testing of Scaled Truck Models Tom Reinhart, Duke Drinkard, Ron Graves, Chuck Salter, Drew Kodjak, Duncan Brown, Steve Lasher

August 12, 2009 Transportation Research Center East Liberty, OH Road Testing of Heavy Duty Vehicles Tom Reinhart, Duke Drinkard, Ron Graves, Steve Lasher2-1 2. Vehicle and Duty Cycle Descriptions

The analysis focuses on fuel efficiency technol ogies for seven different types of medium- and heavy-duty vehicles. These vehicl e types represent a large fraction of total fuel use in the medium- and heavy-duty category, operate over a range of duty cycles, and can benefit from an assortment of the most likely fuel efficiency improvement technologies co nsidered in this study. Although these categories do not capture all of the fuel consumed in the medium- and heavyduty onroad vehicle sector, the sele ction of vehicles represents a significant portion of it. The general vehicle categor ies selected are:

• Class 8 Tractor Trailer

• Class 8 Refuse Hauler

• Class 3-6

– Straight Box Truck

– Bucket Truck

• Urban Transit Bus

• Motor Coach

• Class 2b Pick-up Trucks and Vans
For the purpose of this evaluation, we are using th e truck weight classifica tions as defined by the Department of Transportation as shown in Tabl e 2-1. We have also included EPA weight categories and the associated engine durability require ments [NRC 2008].

Table 2-1. DOT and EPA truck weight classifications
DOT Weight Class Minimum GVWR (lbs) Maximum GVWR (lbs) EPA Category EPA Engine Durability Reqs
Class 1 6,000 Light-Duty N/A Class 2a 6,001 8,500 Class 2b 8,501 10,000 Class 3 10,001 14,000 Class 4 14,001 16,000 Class 5 16,001 19,500 Light HeavyDuty 110,000 Miles, 8 Years

Class 6 19,501 26,000 Class 7 26,001 33,000 Medium HeavyDuty 185,000 Mi, 8 Years

Class 8 33,001 80,000 Heavy HeavyDuty 435,00 Miles, 10 Years, 23,000 Hrs2-2 Table 2-2 compares the relative fu el use and weight class of a vari ety of truck types as identified in the 2002 Vehicle Inventory a nd Use Study [VIUS 2004]. As show n, tractor trailers consume 61 percent of the total fuel in the medium - and heavy-duty category, followed by pickup and vans at 13 percent. The rest of the truck types each consume less th an 5 percent of the total fuel.

Table 2-2. Fuel consumption by vehicle weight class and type [VIUS 2004]
Weight Class Truck Type 2b 3 4 5 6 7 8 % of MD/HD Fuel Consumed Straight Trucks Pickup/Van/SUV z z } } 13 Service/Utility z z } } } } 3 Tow/Wrecker z z z 1 Step Van z z z } } 3 Basic Van z z z z z z 4 Flatbed z z } } z z 4 Refrigerated Van z z 1 Beverage } } <1 Tank Truck z z z 2 Dump Truck } } } } z 5 Refuse Hauler z 2 Concrete z 1
Tractor Trailer z 61
z Primary } Secondary

The following sections provide a brief overview of each of the vehicles evaluated, including, when available, vehicle populati on, descriptions of the primary duty cycles, energy audits, and fuel consumption.

2.1 Class 8 Tractor Trailer
With more than 60 percent of the fuel use in the medium- and heavy- duty market and nearly 98 percent of the Class 8 vehicles in-use, tractor trailers represent the largest segment of heavyduty vehicles in-use today. Line -haul operation – characterized primarily by highway driving on routes that are separated by several hundred mile s –accounts for 60 to 70 percent of the fuel use in this class. The other 30 to 40 percent of the fuel use occurs in other short- and medium-haul regional applications. TIAX’s analys is focuses specifically on the Class 8 tractor trailer’s use as a line-haul truck. The analysis of vehicle tractor trailer aerodyna mics further focuses on the subsegment of the tractor trailer fl eet that pulls 53-foot dry box van trailers, which account for 60 to 70 percent of heavy-duty Class 8 on-road m ileage [VIUS 2004]. Dry box vans can take advantage of a number of aerodynamic improvement devices available, represent a relatively homogeneous body type, and can therefore maximi ze potential fuel efficiency improvements. Other duty cycles (e.g., regional haul or drayage) and other types of traile rs will not achieve the2-3 same benefits from the fuel efficiency technolog ies we have identified. Figure 2-1 shows a Class 8 tractor trailer similar to those considered in this evaluation.

Figure 2-1. Class 8 tractor trailer

The 21 st Century Truck Partnership Roadmap presents an energy audit of a t ypical Class 8 tractor trailer as shown in Table 2-3 [DOE 2000]. Efficiency improvements can focus on each of the energy sources and fall into the following categ ories: tractor aerodynami cs, tires and wheels, weight reduction, engine, transmission and driv eline improvements, driver education, idle reduction, and hybridization.

Table 2-3. Energy balance for a fully loaded Class 8 vehicle operating on a level road at 65 miles per hour for 1 hour a

Energy Sources Baseline (kWh) Baseline (HPh) Engine losses per hour 240 321.8 Auxiliary loads 15 20.1 Drivetrain energy 9 12.1 Aerodynamic energy 85 114 Rolling resistance energy 51 68.4 Total energy used per hour 400 536.4

a from 21 st Century Truck Technology Roadmap [DOE 2000]

A typical line-haul duty cycl e is characterized by high mil eage (upwards of 100,000 miles per year) at highway speeds. The unl oaded vehicle weight of a trac tor trailer is 35,000 to 40,000 lbs. Truck loads may be volume constrained (“cubed out ”), weight constrained (“grossed out” at 80K2-4 lbs), or less than truckload (LTL) . On average, tractor trailers are loaded at 55,000 to 60,000 lbs and are volume limited; however, all three categorie s of truck loads are sign ificant. In addition to over the road fuel use, many line-haul vehicles need to provide “hotel loads” for drivers who sleep on the road – typically 1,600 to 2,400 hours per year. Fuel to meet these hotel loads can consume up to 10% of a tractor tra iler’s total fuel. A typical cruise point for a line-haul tractor trailer range from 60 to 70 MPH, while the average speed (incl uding transient operation) ranges from 55 to 60 MPH; however, these details will vary widely by fleet. Newer tractor trailers have fuel economy that range from 6.5 to 7 MPG, a lthough the fleet average is closer to 6 MPG [VIUS 2002, Sodolsky 2002, Smartway 2009a, Smartway 2009b, Davis 2008].

2.2 Class 8 Refuse Hauler
The analysis also examines potential fuel effici ency improvements for Class 8 refuse haulers as shown in Figure 2-2. Refuse haul ers operate over an urban cycle that is characterized by lowspeed operation with frequent st ops. A typical refuse hauler travels 100 to 150 feet between stops and makes on the order of 500 to 800 stops per day, followed by travel – potentially at highway speeds – to an unloading site [Site Visits ]. However, these parameters will vary widely depending on the density of pick-up locations in the service area. Daily mileage is roughly 50 miles; however, significant additional energy is used in refuse compaction, which accounts for roughly two thirds of a refuse hauler’s fuel budget.

Figure 2-2. Class 8 refuse hauler

2.3 Class 3-6 Box and Bucket Trucks
The Class 3-6 vehicle category includes both stra ight box trucks and bucket trucks, as shown in Figure 2-3. The box trucks are assumed to operate over a “regional haul” duty cycle consisting of both urban and highway driving, with average sp eeds of 25 to 30 MPH, and total daily mileage on the order of 150 to 200 miles. Table 2-4 show s an energy audit for a Class 3-6 box or van truck operating at 40 MPH for 1 hour. It should be noted that a typical box truck duty cycle involves significantly more transient operati on than that reflected in Table 2-4.2-5 Figure 2-3. Class 3-6 box or van truck (left) and bucket truck (right)

Table 2-4. Energy balance for a fully loaded Class 6 Medium duty truck vehicle operating on a level road at 40 miles per hour for 1 hour a

Energy Sources Baseline (kWh) Baseline (HPh) Engine losses per hour 73.1 98.0 Auxiliary loads 1.5 2.0 Drivetrain energy 3.3 4.4 Aerodynamic energy 18.9 25.3 Rolling resistance energy 23.0 30.8 Total energy used per hour 119.8 160.6

a correspondence with Karbowski [2009]

The bucket truck runs over a significantly diffe rent duty cycle—an urban work duty cycle which consists of low mileage (tens of miles per day), urban driving, and extended periods of idling (on the order of 6 hours per day). Based on feedback received during site visits, we have assumed that bucket trucks consume roughly 20% of their fuel at idle and 80% on road [Site Visits].

2.4 Urban Transit Bus
According to the American Public Transportati on Association (APTA), there are more than 65,000 transit buses in operati on throughout the United States [APTA 2009]. These vehicles, shown in Figure 2-4, accrue more than 2.3 billion miles and use more than 670 million gallons of fossil fuels 4 (more than 490 million gallons of diesel) each year. This market segment has long been a target for alternative fuel technologies , and significant documenta tion is available for transit buses on their typical duty cycles for emissi ons, fuel use, and lifecycl e costs. Transit buses

4 Fossil fuels here are defined as diesel, gasoline, LNG, CNG, Biodiesel and other.2-6 a. 40-Foot Transit Bus b. 60-Foot Articulated Bus Figure 2-4. Transit Buses

have helped to pave the way for lower emi ssion technologies and can be leaders in fuel efficiency improvements as well.
For this evaluation, a typical transit bus is assumed to ope rate over a high-mileage (150-250 miles per day) and low-speed (12 MPH average) urban duty cycle with high accessory loads (primarily air-conditioning). Table 2-5 shows an energy audit for a transit bus operating over the Central Business District (CBD) cycle for 1 hour.

Table 2-5. Energy balance for half seated load with air conditioning on 40 ft transit bus (32,000 lbs) operating over the CBD cycle for 1 hour a

Energy Sources Baseline (kWh) Baseline (HPh) Engine losses per hour 86.8 116.4 Auxiliary loads 36.4 48.8 Drivetrain energy 13.4 18.0 Aerodynamic energy 1.3 1.7 Rolling resistance energy 7.2 9.7 Total energy used per hour 145.1 194.6

a from 21 st Century Truck Technology Roadmap [DOE 2000]

2.5 Motor Coach
According to the American Bus Association (A BA), there are more than 33,000 motor coaches operating in the United States [ABA 2009]. With an average fuel economy of 5.7 miles per gallon and an annual average of 56,000 miles per vehicle [Nathan 2008], motor coaches in the United States consume nearly 330 million gallons of fuel each year.2-7 Motor coaches, shown in Figure 2-5, typically operate over the highway in high-mileage, highspeed duty cycles. Occasionally, they also operate in urban cycles.

Figure 2-5. Typical over-the-road motor coach

2.6 Class 2b Pickups and Vans
Class 2b pickups and vans operate over a variety of duty cycles, but often in urban driving cycles of relatively low mileage (tens of miles per day) . Currently, class 2b vehi cle sales are split about evenly between gasoline and diesel engines. Historically, diesels en gines tended to hold approximately 70 percent market share for GMC, Ford, and Dodge Ram trucks. However, due in large part to the high cost of em issions systems and the higher cost of diesel fuel relative to gasoline, the market share of diesel ensures dropped to about 50 percent in 2008. This share could decline further with the new 2010 emi ssions requirements [Visnic 2009]. Figure 2-6 shows typical van and pickup truck app lications in the class 2b category.

Figure 2-6. Examples of class 2b vans and pickup trucks3-1 3. Technology Matrix Description

The technology matrix consists of individual tables for the three different engine classes (11 to 15L diesel, 6 to 9L diesel, and 5 to 8L gaso line) and the seven diffe rent vehicle categories (tractor trailers; refuse hauler s; transit buses; Class 3-6 box a nd bucket trucks; Class 2b pickups and vans; and motor coaches). Each table incorporates benefits of a variety of emission control strategies (SCR and EGR in-cylinder technologies). The matrix tables are included in this section as shown in Table 3-1.

Table 3-1. Technology matrix table descriptions

Table No. Engine or Vehicle Class/Application Table 3-2 11—15L Engines Table 3-3 6—9L Engines Table 3-4 5—8L Engines
Table 3-5 Tractor Trailers
Table 3-6 Refuse Haulers
Table 3-7 Transit Buses
Table 3-8 Class 3 –6: Box and Bucket Trucks Table 3-9 Class 2b Pickups and Vans
Table 3-10 Motor Coaches

Baseline assumptions
In order to clearly define a re ference benchmark against which fuel consumption benefits are measured, the matrix for each engine and ve hicle application includes a number of “2008 baseline” assumptions. These assumptions allo w for reasonable comparison among technologies.
11-15 L engines are assumed to have a peak brake th ermal efficiency of between 41 and 42 percent; depending on the truck’s duty cycle, the actual average brake thermal efficiency over a drive cycle will typically be several percentage points lower than this peak value. The 11-15L engines are also assumed to ope rate using high pressure, direct injection, common rail (1,800 to 2,000 bar) or unit fuel injection (~30,000 psi) sy stems, turbocharging, cooled exhaust gas recirculation (EGR) plus diesel particulate fi lters (DPF), and 190 to 200 bar cylinder pressure.
6-9L engines are assumed to have a peak brake thermal efficiency of between 40 and 41 percent. The 6-9L engines are also assumed to operate using direct injection, common rail fuel systems (1,600 to 2,000 bar), turbocharging, cooled EGR plus DPF, and 170 to 180 bar cylinder pressure.3-2 For the 5-8L gasoline engines , the 2008 baseline assumptions in clude port-fuel injection, fixed valve, and no turbocharging.
Each of the vehicle application matrix tables inco rporates variations of th ree sets of assumptions: aero and tire; engine; and dr iveline and idle/accessory.

The Tractor Trailer baseline is assumed to have a C D of 0.59 to 0.6, a C rr of 0.0068, full roof fairings, a sloped hood, aero bumpers, and no undertreatment [Salari 2009, Marinko 2009, NESCCAF 2009]. The trailer is assu med to be a 53-foot standard box trailer with standard dual tires and steel wheels. The tractor is powered by an 11-15L engine with the associated assumptions described above. The trucks are assumed to operate using a 10-speed manual transmission with over-drive, low-speed idle but no anti-i dle technologies, mechanical accessories, limited “driver-management” tools, and governors at 75 MPH.

The 2008 baseline Refuse Haulers are assumed to have no aero-sha ping, standard dual tires with steel wheels, 6-speed automatic transmissi on, and a hydraulic power take-off (PTO).

The 2008 baseline 40-ft Transit Buses operate using a 6-9L engi ne as described above. Additionally, they are assumed to be equipped wi th standard dual tires, steel wheels, no aeroshaping, 6-speed automatic transmission, low-sp eed idle and no anti-i dling technologies, mechanical accessories, and limited “driver-management” tools.

The Class 3-6 Box and Bucket Trucks are assumed to run on 6-9L engines as described above and have standard dual tires and steel wheels. The baseline vehicles are assumed to have no aero add-on devices but some cab streamlining. Like th e transit buses, it is assumed that the box and bucket trucks are equipped with 6-speed automa tic transmission, low-spee d idle but no antiidling technologies, mechanical accessories , and limited “driver management” tools.

The baseline Class 2b Pickup and Truck assumptions 6-8L gasoline engines with natural aspiration, port fuel injection, a nd 4-speed automatic transmission.

Motor Coaches are assumed to use an 11-15L engine. As with the transit buses and box and bucket trucks, the motor coaches evaluated here are equipped with stan dard dual tires, steel wheels, 6-speed automatic transmission, low-sp eed idle and no anti-idling technologies, mechanical accessories, and limited “driver-management” tools.

How to interpret the tables

Definitions of each column in the matrix tables are as follows:
Category: Indicates the broad class of fuel reduction strategies to which the specified technology applies. Examples include “Aerody namics”, “Transmission & Driveline”, etc.
Technology: An individual fuel consumption reduc tion strategy that could be deployed into medium- and heavy-duty vehicles within the next ten years.3-3 Fuel consumption (FC) benefit: The reduction in fuel consump tion associated with adopting a given technology. The fuel consumption be nefit of “A” is defined as follows:

A baseline

baseline

A benefit MPG MPG FC

FC FC

− = − = 1

1 Equation 1

The relationship between the percent fuel consum ption (FC) benefit and the fuel economy (FE) benefit of a technology is as follows:

benefit benefit FE FC % 1 1 1 % + − = Equation 2

The fuel consumption benefit reflects the reduc tion in fuel consumption that an owner would expect to see on a typical duty cycle for the given application. A short description of the typical duty cycle for each vehicle type is included in Ch apter 2. A range in the fuel consumption benefit reflects both variations in the technology configuration (for ex ample, a larger waste heat recovery system would recapture more energy); and/or variations due to duty cycle conditions. The source for fuel consumption benefit estima tes are described in Section 4 on a technology-bytechnology basis.
Capital cost: For technologies that are currently on the market, our estimates indicate the actual price that consumers typically pa y. For future technologies, our es timates are expressed in terms of a “retail price equivalent” (R PE). All costs are estimated in 2009 dollars. The RPE reflects the marginal cost that a truc k buyer would expect to pay to purchase a given technology 5 , and includes the following factors:

• Amortized ex-factory cost

• Factory overhead and mark-up, including wa rranty, research and development (R&D), marketing and sales, engineering, depreciati on, legal, corporate overhead, retirement and health benefits, accounting, shipping and dist ribution, corporate taxe s and dealer support

• Dealer discount or mark-up

• Profit
The cost estimates do not include additional ope rating and maintenance (O&M) costs. In some cases, for currently available technology, the “list price” of a te chnology was provided by manufacturers or dealerships. Indus try feedback suggested that the selling price is typically about 60 percent of the list price, so these list prices were multiplied by a factor 0.6. For technologies that are not currently on the market, or are on the market in low numbers, both low volume and high volume costs were included.

5 Prices include installation costs, except for trailer aerodynam ic devices, which are currently sold as after-market “add-ons” . If these devices become widely adopted, they will become standar d options on new trailers, which will greatly reduce the installation cost.3-4 It should also be noted that transit bus hybrid systems appear to be priced significantly higher than their actual component costs would indicate. We speculate that this is due in part to the 90% government subsidy of hybrid bus technology, wh ich allows the market to bear significantly higher costs than an unsupported market; it may al so be due to low production volumes. Hence, for the specific case of transit hybrid technologies, we have incl uded information as to both the subsidized and unsubsidized costs of transit buses.
A range in capital cost for a given technology can re flect any of several diffe rent factors. These include:

• Variations between different conf igurations of a given technol ogy (For example, trailer side skirt designs range from simple “belly boxes” to automatically retractab le, flexible skirts.)

• Uncertainty in the cost of the technology – this applies to t echnologies that are not yet in production (For example, advanced engine techno logies such as next-g eneration fuel systems or onboard diagnostics.)

• A combination of both uncertainty and design variation (For example, bottoming cycle systems are still under development; moreover, they can be sized to reco ver varying levels of waste heat, and can be implemented as either an electric or a mechanical system.)
The meaning of ranges in technology cost will be described in the text on a technology-bytechnology basis.

C d /C rr /Wt Change: Identifies the effect, if any, that a given technology has on the vehicle’s aerodynamic drag, coefficient of ro lling resistance, or weight.

Intro Year: This column reflects the year in which the technology is expected to be introduced. These are based on data from technology roadmaps from suppliers when available and on estimates for cases in which technologies are to o distant to be included in actual production plans. Some technologies included in the tabl e, such as improved combustion chamber design that allows increased cylinder pressure or stream lining of the tractor aero dynamics, do not reflect a discrete introduction of new t echnology but rather evolutionary changes to existing designs. In these cases, technology is incrementally impr oved with each successive technology generation. For these types of continually improving technologi es, the year of intro duction is said to be “continuous” in the table.
Market penetration: Where available, the market penetra tion identifies the adoption rate of a technology in 2008. Technologies th at are on the market in li mited, pre-production quantities (ranging from single vehicle to a few hundred) are identified as “demos”.

Baseline: This column lists the technology or vehi cle configuration agai nst which the fuel consumption and incremental cost are measured.

Reference: Identifies the section of the report in which the given technology is discussed.3-5Table 3-2. 11 to 15L engine technology matrixDescriptionFC Improvement Capital cost (RPE) Intro Year Baseline Section No.AReduce Heat Transfer and Exhaust Losses4.1.3.2A.1 High pressure fuel injection (up to 4,000 bar), multiple injections per cycle, rate shaping, etc 1 to 4% $0 to $1,000 Continuous 1,800 to 2,200 bar; single injection/ cycle; common rail or unit FIA.2 Increase cylinder pressure1 to 3% $500 to $1,500 Continuous 20 to 23 BarA.3 OBD w/Engine controls and sensors — closed loop control, run engine @ NOx limits across the map 1 to 3% $60 to $150 2013 Open-loop electronic controlsA.4Emissions Control4.1.3.1A.4.1 Add SCR (optimizes engine for efficiency, not NOx) – includes 2% DEF penalty 2 to 3% $9,000 to $10,000 2010 Medium-rate EGR (2007-compliant)A.4.2 Improved NOx conversion efficiency1 to 3% $0 Continuous, post 2010Cu-zeolite or Fe-zeolite for 2010; better catalysts, lower light-off temp canyield future benefitsA.4.3 Passive DPF regen and reduced back pressure1 to 1.5% $0 2010 Active RegenA.4.4 High-Rate EGR-1 to -2% $8,000 2010 Medium-rate EGR, (2007-compliant)A.4.5 Mixed-mode advanced combustion — (e.g., PCCI @ low/med load) 1 to 2% $10,000 2012 to 2015 Medium-rate EGR, (2007-compliant)Subtotal NOx/Fuel efficiency/Particulate Trade-off TechnologiesUp to 6% $9,000 to $10,000 Continuous Medium-rate EGR, no SCR,Active regenTotal Heat Transfer and Exhaust Loss Reduction Technologies up to 10% $9,000 to $12,650 Continuous ~41 to 42% thermal efficiencyBReduce Gas Exchange Loss Reduction4.1.3.3B.1 VVA1% $300 2012B.2 Advanced low-temperature EGR, lower pressure drop 1 to1.5% $500 to $750 2010 to 2013 Medium rate cooled EGR, negative delta pB.3 Turbocharger efficiency oradvanced configurations (e-turbo, multi-stage, etc) 1 to 2% $0 to $1,000 Continuous VG turbochargerTotal Gas Exchange Loss Reduction Technologies up to 3% $0 to $2,050 Continuous ~41 to 42% thermal efficiency lossCReduce friction - lubricants, bearings, etc4.1.3.4Total Friction Reduction Technologies 0.5 to 2% 0 to $500 Continuous ~41 to 42% thermal efficiency lossDReduce Parasitic and Accessory Loads4.1.3.5D.1 Incremental improvements to existing baseline0 to 0.5% $0 to $200 Continuous Belt-driven mechanical accessoriesD.2 Variable displacement pumps, incremental improvements1 to 2% $200 to $500 2012 Belt-driven mechanical accessoriesD.3Accessory Electrification — Electric Auxiliaries (alternator, air compressor, power steering pump, aircond, fan, fuel pump, water pump); in combination with hybrid or other vehicle electrification.1 to 3% $1,000 to $2,000 2012 Belt-driven mechanical accessoriesTotal Parasitic and Accessory Loads Reduction Technologies 0 to 3% $0 to $2,000 Continuous ~41 to 42% thermal efficiency lossERecover Waste Heat4.1.3.6E.1 Turbo-Compound – Mechanical2.5 to 3% $2,000 to $3,000 2010 No WHRE.2 Electric Turbo-Compound, includingaccessory electrification 4 to 5%$6,000 to $7,000($3,000 to $4,000 inc.to Hybrid)2013 No WHRE.3 Thermo-electric or thermo-acoustic2 to 3% ? 2015 No WHRE.4 Bottoming Cycle, Steam Cycle or ORC – 15 to 60 kW 6 to 10% $7,200 to $15,100 2015 No WHRTotal Waste Heat Recovery Technologies 2.5 to 10% $2,000 to $16,000 2010 No WHR3-7Table 3-3. 6 to 9L engine technology matrixItem Description FC Improvement Capital cost (RPE) Introduction Baseline Section No.AReduce Heat Transfer and Exhaust Losses4.1.3.2A.1 High pressure fuel injection (up to 4,000 bar), multiple injections per cycle, rate shaping, etc 1 to 4% $0 to $1,000 Continuous 1,800 to 2,200 bar; single injection/ cycle; common rail or unit FIA.2 Increase cylinder pressure1 to 4% $500 to $1,500 Continuous 20 to 23 BarA.3 OBD w/Engine controls and sensors — closed loop control, run engine @ NOx limits across the map 1 to 4% $60 to $150 2013 Open-loop electronic controlsA.4Emissions Control4.1.3.1A.4.1Add SCR (optimizes engine for efficiency,not NOx) – includes 2% DEF penalty2 to 3%$7,000 to $8,0002010Medium-rate EGR (2007-compliant)A.4.2 Improved NOx conversion efficiency1 to 3% $0 Continuous, post 2010Cu-zeolite or Fe-zeolite for 2010; better catalysts, lower light-off tempcan yield future benefitsA.4.3 Passive DPF regen and reduced back pressure1 to 1.5% $0 2010 Active RegenA.4.4 High-Rate EGR-1 to -2% $6,000 2010 Medium-rate EGR, (2007-compliant)A.4.5 Mixed-mode advanced combustion — (e.g., PCCI @ low/med load) 1 to 2% $8,000 2012 to 2015 Medium-rate EGR, (2007-compliant)Subtotal NOx/Fuel efficiency/Particulate Trade-off Technologies (assumes SCR) Up to 6% $7,000 to $8,000 Continuous Medium-rateEGR, no SCR, Active regenTotal Heat Transfer and Exhaust Loss Reduction Technologies up to 12% $7,000 to $9,650 Continuous ~40 to 41% thermal efficiencyBReduce Gas Exchange Losses4.1.3.3B.1 VVA1% $300 2012B.2 Advanced low-temp EGR, lower pressure drop0 to 1.5% $500 to $750 2010 to 2013 High-rate EGRB.3 Turbocharger efficiency and performance enhancements; e-turbo,super-charging, etc 1 to 3% $0 to $1,000 Continuous Multi-stage elec. actuated turboTotal Gas Exchange Losses Reduction Technologies up to 4% $0 to $2,050 Continuous ~40 to 41% thermal efficiencyCReduce Friction - lubricants, bearings, etc4.1.3.4Total Friction Reduction Technologies 0.5 to 2% 0 to $500 Continuous ~40 to 41% thermal efficiencyDReduce Parasitic and Accessory Loads4.1.3.5D.1 Incremental improvements to existing baseline0 to 0.5% $0 to $200 Continuous Belt-driven mechanical accessoriesD.2 Variable displacement pumps, incremental improvements 0.5 to 2% $200 to $500 2012 Belt-driven mechanical accessoriesD.3Accessory Electrification -- ElectricAuxiliaries (air compressor, power steering pump, air cond, fan,alternator, water pump); in combination withhybrid or other vehicle electrification.1 to 3%$1K to $2K (Low)$500 to $1,000 (High)2012 Belt-driven mechanical accessoriesTotal Parasitic and Accessory Loads Reduction Technologies 0 to 3% $0 to $2,000 Continuous ~40 to 41% thermal efficiency3-9Table 3-4. 5 to 8L gasoline engine technology matrixDescriptionFC Improvement Capital cost (RPE) Introduction Baseline Section No.A/BReduce Gas Exchange, Exhaust Heat, and Heat Transfer Losses4.1.5.2A/B.1 VVT1 to 3% $122 2008 Gasoline, PFI, fixed valve w/reduced frictionA/B.2 VVL (Discrete or Continuous)1 to 3.5% $400 to $750 2008 Above + VVTA/B.3 Stoichiometric GDI2 to 3% $512 to $930 2008 Above + VVL + Cylinder deactivationA/B.4 Lean burn GDI10 to 14% $750 2012 + low sulfur fuel Stoichiometric GDIA/B.5 Turbo-charged, down-sized engine2.1 to 2.2% $1,229 2008 Stoichiometric GDIA/B.6 Cylinder deactivation2.5 to 3% $75 2008 Baseline + VVL and VVT + reduced frictionA/B.7 Gasoline HCCI10 to 12% $685 ? Stoichiometric GDITotal Gas Exchange, Exhaust Heat, and Heat Xfer Loss Reduction Technologies Up to 15% $0 to $4,200 Continuous Gasoline, PFI, fixed valveCReduce Friction - lubricants, bearings, etc4.1.5.2Total Friction Reduction Technologies 0.5 to 2.5% $110 to $500 Continuous Gasoline, PFI, fixed valveDReduce Parasitic and Accessory loads4.1.5.2D.1 Variable displacement pumps, incremental improvements 0.5 to 2% $200 to $500 2012 Belt-driven mechanical accessoriesD.2Accessory Electrification — Electric Auxiliaries (aircomp, ps pump, air cond, fan, alt, water pump); incombination with upgrade to 42V electrical system or hybrid.1 to 3%$1,000 to $2,000(current)$500 (high volume)2012 Belt-driven mechanical accessoriesTotal Parasitic and Accessory Load Reduction Technologies 0 to 3% $0 to $2,000 Continuous Belt-driven mechanical accessories3-11Table 3-5. Tractor trailer technology matrixCategoryTechnologyFC BenefitCd/Crr/WtChangeCapital cost (RPE)Intro YearSalesPen.VocationBaselineSectionNo.Load ReductionRoof top fairing, sleeper cab7 to 10% 15 to 20%(Standard)$500 to $1,000pre-2008 63% Van TT onlyNo cab aero 4.2.2.1Roof top deflector, day cab4 to 7% 13% $1,000 to $1,300 pre-2008 MostDay cabs only No cab aero 4.2.2.1Cab Side extension (aka, "side fairing") 2 to 3% 4 to 5%$300 to $500; (Standard onsome vehicles)pre-200880 to90%Any No cab aero 4.2.2.1Chassis Skirts (aka, "chassis fairing", "fuel tank fairing") -— full length 3 to 4% 4 to 7% $1,500 to $2,000 pre-2008Long Haul,sleeper cabsNo cab aero 4.2.2.1Chassis Skirts (aka, "chassis fairing", "fuel tank fairing")— partial length 2 to 3% 4 to 6% $500 to $1,200 pre-200845 to60%Day cabsprimarilyNo cab aero 4.2.2.1Baseline Package - Smartway Aero Cab: Aero mirrors, cab side extenders, integrated sleepercab roof fairing, aero bumper, full fuel tank fairings;4 to 6% 22 to 25% $2,750 to $3,500 2008 to 2010 ~60% Van TT, primarilyCompared to no aero(CDof 0.8)4.2.2.1

Tractor Aero"Next generation" Smartway aero cab: Current Smartway cab, PLUS aero bumperw/underbody treatment; improved streamlining; wheel skirts3 to 4% beyondSmartway6 to 8% $2,750 2012 — Van TT, primarily Smartway cab 4.2.2.1Partial Skirts (4 to 6 m)2 to 3%2 to 6%$1,500 to $2,0002010 to 2012DemosMany types oftrailers53' box trailer 4.2.2.4Full Skirts (7 to 9 m)4 to 5%5 to 11%$2,000 to $4,0002010 to 2012 DemosMany types oftrailers53' box trailer 4.2.2.4Partial Gap Fairing1 to 2%2 to 4%$800 to $1,0002010 to 2012DemosVan TT 53' box trailer; 42" gap —Full Gap fairing2 to 3% 4 to 6% $1,000 to $1,500 2010 to 2012 Demos Van TT 53' box trailer; 42" gap —Boat tail — structural or inflatable 4 to6% 6.5 to 9% $1,500 to $2,000 2010 to2012 Demos Van TT 53' box trailer 4.2.2.5Bogie Fairing – fairing for the trailer rear wheel assembly1% ~2% $500 2010 to 2012 Demos Any 53' box trailer 4.2.2.4Hub caps0 to 0.5% ~1% ? 2010 to 2012 Demos Any 53’ Box trailer 4.2.2.6Pneumatic Aero Drag Reduction - Unproven3.5 to 4.0% ? $2,500 - $5,250 Post-2015 Demos Van TT53' box trailer 4.2.2.6Smartway trailer – partial skirts + partial gap fairing or boattail 5 to 6% 10 to 12% $3,000 per trailer 2010 to 2012 Demos Van TT 53' box trailer 4.2.2.2

Trailer AeroFull next-generation trailer aero – full skirts,boat tail, and full gap fairing 8 to 9% 17 to 19% $4,000 per trailer 2013 to 2015 — Van TT 53' box trailer 4.2.2.2No aero-10 to -12%-22 to -25%-Pre-2008— Van TTSmartway Tractor, 53’trailer4.2.2.8Smartway Tractor-CD~ 0.59-Pre-2008~60% Van TTSmartway Tractor, 53’trailer4.2.2.8Smartway Tractor + Smartway Trailer5 to 6%10 to 12%$3,000 per trailer2010 to2012Demos Van TTSmartway Tractor, 53’trailer4.2.2.8Improved Smartway Tractor + Smartway Trailer7 to 9%15 to 17%$2,750 + $3,000 per trailer2012 to2013Demos Van TTSmartway Tractor, 53’trailer4.2.2.8

Tractor + Trailer Aero PkgsFull Aero Tractor & Trailer11 to 12%22 to 24%$2,750 + $4,000 per trailer2013 to2014— Van TTSmartway Tractor, 53’trailer4.2.2.83-13Table 3-5. Tractor trailer technology matrix (continued)CategoryTechnologyFC BenefitCd/Crr/WtBenefitCapital cost (RPE)Intro YearSalesPen.BaselineSection No.Flat-nose Trailer 3 to 4% 7% - - ~20% Smartway Tractor 4.2.2.1Double trailer-10% - - - 53' single 4.2.2.1Fender-mounted mirrors, bug deflector, etc. -1.5 to-3% - - - 53' box trailer 4.2.2.1

Aero PenaltiesCattle hauler, car hauler, flatbed -5 to -13% -10 to -30% - - - 53' box trailer 4.2.2.1Low Rolling Resistance Smartway Duals, tractor and trailer 2 to 3%9%$30 per tire 2008 60 to 70% steel std duals 4.3.3.1Low rolling resistance WBS Tires w/aluminum wheels, Tractor only 3to 6% 19% $225 per wheel + tire 2008 5% steel std duals 4.3.3.1Low rolling resistance WBS Tires w/aluminum wheels, Tractor + Trailer 6 to 9%19%$225 per wheel + tire 2008 5%steel std duals 4.3.3.1Next-generation dual 4 to 5% 15% $30 per tire 2013 to 2015 — steel std duals 4.3.3.1Next-generation WBS (Tractor Only) – Crr 0.0045 8 to 11% 33%$225 per wheel + tire 2013 to2015 — steel std duals 4.3.3.1Next-generation WBS (Tractor+trailer) – Crr 0.0045 11 to 14% 33%$225 per wheel + tire 2013 to2015 — steel std duals 4.3.3.1Tractor tire monitor 0.6% $100 2008? 5 to 10 psi Underinflated 4.3.3.1Tractor ATI0.6% $4,000 to $5,000 2008 ? 5to 10 psi Underinflated 4.3.3.1

Tires and WheelsTrailer ATI0.6% $300 to $400 2008 ? 5 to10 psi Underinflated 4.3.3.1WBS + aluminum wheels — benefit is included in WBS line item under tires 0 to 0.3% 100 lbs per tire $225 per wheel + tire 200810% aluminum duals 4.4.2Volume-constrained0 to 1,000 lbs1,000 to 2,000 lbs2,000 to 3,000 lbs0.4 to 0.6% Per 1,000 lbs$2 to $4/lb$4 to $8/lb$8 to $10/lbContinuous — 65K lb GVW 4.4.2

Weight ReductionWeight-constrained0 to 1,000 lbs1,000 to 2,000 lbs2,000 to 3,000 lbs2.2% Per 1,000 lbs$2 to $4/lb$4 to $8/lb$8 to $10/lbContinuous — 80K lb GVW 4.4.2Powertrain2010 engine – 43.2 to 44.2% 4 to 5% +400 to 500lbs $9.6 to $10.6K 2010— 2007-2008 15L engine 4.1.4.12013 engine – 45.5 to 47.5% 9 to 12% +50 lbs$13.2 to $15.2K 2013 — 2007-2008 15L engine 4.1.4.22015 engine – 47.9 to 51.4% 13 to 18% +450 to 550 lbs $14.7 to $18.2K 2015 — 2007-2008 15L engine —

Engine (13 to 16L)2020 engine – 47 to 51% 18 to 22% +600 to 800 lbs$21.4 to $25.9K 2020 —2007-2008 15L engine 4.1.4.43-15Table 3-5. Tractor trailer technology matrix (continued)CategoryTechnologyFC BenefitCd/Crr/WtBenefitCapital cost (RPE)Intro YearSalesPen.VocationBaselineSection No.Appropriate spec-ing of truck: matchthe axles, transmission gears, etc forthe intended route, road speeds, and vocation*1 to 3% — Pre-2008 60-90% Any10-speed manual, matchedaxles and gears4.5.1Direct Drive 1 to 1.5% — — Pre-2008 ? Any10-speed manual, matchedaxles and gears4.5.1Friction Reduction 1 to 1.5% — $0 to $500 Continuous — Any10-speed manual, matchedaxles and gears4.5.1Single drive axle 1% — $200 to $300 2012-2013 — Any10-speed manual, matchedaxles and gears4.5.1Automatic transmission 0 to 5% +200 lbs $15,000 2008 <5% Regional haul10-speed manual, matchedaxles and gears4.5.1

Transmission and DrivelineAMT/Optimized Shift Strategy 4 to 8% +70 lbs $4,000 to $5,700 2008 10% Any10-speed manual, matchedaxles and gears4.5.1Route Management – telematics for congestion & weather avoidance 0 to 1% — $400 to $800 2010 — Any No route management 4.8Engine & Driveline Management (load-based speed control, multi-torque) 1 to 2% — —2009 ? Long haul Non-controlled engine 4.8Adaptive cruise control — Slows according to traffic 0 to 1% —$2,000 to $3,000 pre-2008 10% LongHaul basic cruise control 4.8Predictive cruise control — adjusts vehicle according totopology, conditions 1 to 2% — $100 2012 — Long Haulbasic cruise control +Telematic GPS system4.8Speed Governor - 60 MPH0.4 to 0.5% perMPH— — pre-2008 25 to 50% Long Haul 70MPH speed 4.8

Driver Management and CoachingTraining & Feedback — driving training, sweet-spot indicator, rewards, etc 1 to 4% — $0 to $1,600 Continuous 25 to 50% Long Haul No coaching 4.8Automatic Engine Idle Management - 0.5 gal/hr, 1,500 to2,400 hrs/yr 3% — $1,000 to $4,000 2008 ? Long Haul1,500 to 2,400 hours per yearidling; 0.8 gal/hr4.7Direct fire heater - saves 0.2 to 0.3 gal/hr 500 to 800hrs/yr 1.3 to 2.3% — $1,000 - $3,000 2008 ? Long Haul1,500 to 2,400 hours per yearidling; 0.8 gal/hr4.7Battery System – 0 gal/hr, ~10 hours of life; requires off-board charging 5 to 9% 400 to 500 lbs $3,000 to $8,000 2008 ? LongHaul1,500 to 2,400 hours per yearidling; 0.8 gal/hr4.7

Idle Reduction PackagesAPU – 0.2 to 0.3 gal/hr, 1,500 to 2,400 hrs/yr 4 to7% 400 to 500 lbs $6,000 to $8,000 2009 ? Long Haul1,500 to 2,400 hours per yearidling; 0.8 gal/hr4.7"Moderate Hybrid": Dual mode, all electric capability; Includes electrifiedaccessories, overnight hotel loads, and engine-off at idle6 to 9% ~750 lbs$45 to $5K (Low)$25 to $30K (High)2013 Demos Any 2007 Base engine 4.6.4.4"Mild Hybrid": 40 to 50 kW motor;Parallel, single motor and clutch;integrated hybrid assembly (motor, clutch, transmission) and powerelectronics (battery, inverters, controls); Includes electrified accessories,hotel loads, and engine-off at idle5 to 7% ~ 500 lbs$35 to $45K (Low)$20 to $25K (High);2013 Demos Any 2007 Base engine 4.6.4.4

Hybrid PackagesGen II hybrid: Integration w/engine and after-treatment — optimize engineoperation; implemented on either hybridpackage. Requires reg. change.2 to 3% — — 2014-2015 — Any Hybrid package 4.6.4.43-17Table 3-6. Refuse hauler technology matrixCategoryTechnologyFC BenefitCd/Crr/WtChangeCapital cost (RPE)Intro YearSalesPen.BaselineSection No.2010 engine – Peak efficiency of 43.2 to 44.2% 4 to 5% +400 to 500 lbs $9.6 to $10.6K 2010—2007-2008 15L engine (see abovedescription)4.1.4.12013 engine – Peak efficiency of 45 to 46.5% 8 to 10% +400 to 500 lbs $11.2 to $12.2K 2013—2007-2008 15L engine (see abovedescription)4.1.4.22015 engine – Peak efficiency of 47.2 to 49.2% 12 to 15% +400 to 500 lbs $12.7 to $14.2K 2015—2007-2008 15L engine (see abovedescription)—

Engine (11L to 13L)2020 engine – Peak efficiency of 47.6 to 50.3% 13 to 16% +400 to 500 lbs $13.4 to K14.9K 2017 to 2020—2007-2008 15L engine (see abovedescription)4.1.4.4Appropriate spec-ing: match the axles, transmission gears to the application 1 to 3%——Pre-200860 to100%6 speed AT 4.5.2Increased Transmission Gears – 6 spd to 8 spd AT 2 to 3%—$2,100 to $2,600 2010—6 speed AT 4.5.2Reduced AT parasitics and friction 1%—0 to $500 Continuous—6 speed AT 4.5.2

Transmission and DrivelineAggressive Shift Logic and Early Lockup 0.5 to 1%—$100 2010—6 speed AT, Conventional shiftstrategy4.5.2Parallel HEV 20% 450 lbs $35-$40K (Low) 2009—No Hybrid 4.6.4.3Parallel HEV, Future 25 to 30% 350 lbs $18-$20K (High) 2014—No Hybrid 4.6.4.3Parallel HEV, ePTO 25% 650 lbs $52K 2010—No Hybrid 4.6.4.3Parallel HEV, Future 30 to 35% 500 lbs $25 to $30K 2014—No Hybrid 4.6.4.3Parallel HHV 20 to 25% 1,000 lbs $40K (Low)$30K (High)2009—No Hybrid 4.6.4.3Series HHV 40 to 50% ~1,500 lbs$50K (Low)$40K (High)2013—No Hybrid 4.6.4.3

HybridsIntegration of emissions control w/hybrid system 2 to 3%——2014-2015—No Hybrid 4.6.4.3Low Rolling Resistance Smartway Dual Tires 1.2 to 1.8% 9% $30 per tire 2008—standard duals – Crr = 0.0068 4.3.3.5Next generation low rolling resistance duals 2.4 to 3% 15% $30 per tire 2013—standard duals – Crr = 0.0068 4.3.3.5

Tires and WheelsTire Inflation Monitor0.36%—$1002010—5-10 PSI Underinflated4.3.3.5WeightReduction0 to 1,000 lbs1,000 to 2,000 lbs1.4 to 2.3%Per 1,000 lbs$4 to $8/lb$8 to $10/lbContinuous—80K lb GVW4.4.63-19Table 3-7. Transit bus technology matrixCategoryTechnologyFC BenefitCd/Crr/WtChangeCapital cost (RPE)Intro YearSalesPen.BaselineSection No.2010 engine – Peak thermal efficiency of 41.7 to43.2% 4 to 5% +300 lbs $7.6 to $8.6K 2010 —2007 emissions compliantengine4.1.4.12013 engine – Peak thermal efficiency of 43.4 to45.4% 8 to 10% +300 lbs $9.8 to $10.8K 2013 —2007 emissions compliantengine4.1.4.22015 engine – Peak thermal efficiency of 45.4 to 48.1% 12 to 15% +300 lbs $11.5 to $13K 2015 —2007 emissions compliantengine—

Engine (8 to 9L)2020 engine – Peak thermal efficiency of 45.9 to49.1% 13 to 16.4% +300 lbs $12.2 to 13.7K 2020 —2007 emissions compliantengine4.1.4.4Appropriate spec-ing: match the axles, transmission gears to theapplication1 to 3% — — Pre-200860 to100%6 speed AT 4.5.2Increased Transmission Gears – 6 spd to 8 spd AT 2 to3% — $1,100 to $1,650 2010 ? 6 speed AT 4.5.2Reduced AT parasitics and friction 1% — 0 to$500 Continuous — 6 speed AT 4.5.2

Transmission and DrivelineAggressive Shift Logic and Early Lockup 0.5 to 1% — $100 2010 —6 speed AT, Conventional shiftstrategy4.5.2Gasoline Series: 270 kW engine, 200 kW generator, 170 kW motor,200 kW NiMH battery or ultracap25 to 35% 2,000 lbs$200,000($20K w/90%subsidy)Pre-2008150 onthe roadNo Hybrid 4.6.4.5Diesel Series: 270 kW engine, 200 kW generator, 170 kW motor, 200kW NiMH battery or ultracap30 to 40% 2,600 lbs$220,000($22K w/subsidy)Pre-200875 on theroadNo Hybrid 4.6.4.5Diesel Parallel 22 to 35% 940 to 2,840$200,000($20K w/subsidy)Pre-200825 to30%No Hybrid 4.6.4.5

HybridIntegration of emissions control w/hybrid system 2 to 3% — — 2014 — No Hybrid 4.6.4.5Low Rolling Resistance Smartway Dual Tires 0.8 to 1.2%9% $30 per tire 2008 — standard duals – Crr = 0.0068 4.3.3.4Next generation low rolling resistance duals 1.6 to 2% 15%$30 per tire 2013 — standard duals – Crr = 0.0068 4.3.3.4

Tires and WheelsTire Inflation Monitor 0.25% ? $1002010 — 5-10 PSI Underinflated 4.3.3.4WeightReduction0 to 800 lbs800 to 1,600 lbs1,600 to 2,800 lbs2 to 3% Per 1,000 lbs$2 to $4/lb$4 to $8/lb$8 to $10/lbContinuous — 28.5K lb GVW 4.4.33-21Table 3-8. Class 3-6 box and bucket truck technology matrixCategoryTechnologyFC BenefitCd/Crr/Wt ChangeCapital cost(RPE)Intro YearSales Pen.BaselineSection No.2010 engine – Peak thermal efficiency of 41.7 to43.2% 4 to 5% +300 lbs $7.6 to $8.6K 2010 —2007 emissions compliant engine4.1.4.12013 engine – Peak thermal efficiency of 43.4 to45.4% 8 to 10% +300 lbs $9.8 to $10.8K 2013 —2007 emissions compliant engine4.1.4.22015 engine – Peak thermal efficiency of 45.4 to 48.1% 12 to 15% +300 lbs $11.5 to $13K 2015 —2007 emissions compliant engine—Engine (6 to 9L)2020 engine – Peak thermal efficiency of 45.9 to49.1% 13 to 16.4% +300 lbs $12.2 to 13.7K 2020 —2007 emissions compliant engine4.1.4.4Roof Deflector2 to 3% 7 to 7.5% $500 to $800 2008 <1% 4.2.3Fuel Tank/Chassis fairings0.5 to 1% 2.5 to 3% $400 to $500 2010-2012—4.2.3Box Skirts2 to 3% 4.5 to 5% $500 to $1,000 2010-2012 Demos 4.2.3Cab side extension or Cab/Box Gap fairing (e.g., Nosecone)0.5 to 1% 2.4 to 2.7% $500 to $650 2010-2012 Demos 4.2.3Aft Box Taper1.5 to 3% 7.6 to 8% $1,000 2014-2015—4.2.3Cab streamlining: aero mirrors,aero bumper, streamlined shape1 to 2% 5 to 6% $750 2010-2012—4.2.3AeroStraight Truck aero combination package5 to 8% 20% $3,000 to $3,500 2015—No aero add-on devices;4.2.3Low Rolling Resistance Smartway Dual Tires1.4 to 2.1% 9% $30 per tire 2008 ? standard duals – Crr = 0.0068 4.3.3.3Next generation low rolling resistance duals2.8 to 3.5% 15% $30 per tire 2013 - standard duals – Crr = 0.0068 4.3.3.3Tire Inflation Monitor0.42%?$1002010-5-10 PSI Underinflated4.3.3.3Tires and WheelsLow rolling resistance wide base single (WBS) w/aluminum wheels2.1 to 4.2% 12%$225 per tire +wheel2008 - standard duals – Crr = 0.0068 4.3.3.3Appropriate spec-ing: match the axles, transmission gears to theapplication1 to 3% — — Pre-2008 60 to 100% 6 speed AT 4.5.2Increased Transmission Gears – 6 spd to 8 spd AT2 to 3% — $1,000 to $1,650 2010 ? 6 speed AT 4.5.2Reduced AT parasitics and friction1% — 0 to $500 Continuous — 6 speed AT 4.5.2Transmission andDrivelineAggressive Shift Logic and Early Lockup0.5 to 1% — $100 2010 — 6 speed AT, Conventional shift strategy 4.5.2WBS + aluminum wheels -- benefit is included in WBS line item undertires0.1% for 4wheels~100 lbs pertire+wheelSee WBS undertires2008 ? steel duals 4.4.5Weight Reduction0 to 470 lbs470 to 940 lbs940 to 1,650 lbs3 to 5%Per 1,000 lbs$2 to $4/lb$4 to $8/lb$8 to $10/lbContinuous—16.5K lb GVW4.4.5Parallel HEV 20 to 25% 450 lbs $35-$40K (Low) 2007 ~1 to 2% No Hybrid Technology4.6.4.1Parallel HEV, Future (Engine-off atidle, electric accessories, optimizedcontrols, lighter components, high volume production)25 to 35% 350 lbs $18-$20K (High) 2014 - No Hybrid Technology4.6.4.1Parallel HHV 20 to 25% 1,000 lbs$40K (Low)$30K (High)2011 - No Hybrid Technology4.6.4.1Series HHV 40 to 50% ~1,500 lbs$50K (Low)$40K (High)2013 - No Hybrid Technology4.6.4.1Parallel HEV w/ePTO 30 to 40% 650 lbs $49 to $52K (Low) 2007 ~1 to 2% No Hybrid Technology4.6.4.2HybridParallel HEV w/ePTO, Future ((Engine-off at idle, electric accessories,optimized controls, lighter components, high volume production)35 to 45% 500 lbs$25 to $30K(High)2014 - No Hybrid Technology4.6.4.23-23Table 3-9. Class 2b pickup and van technology matrixCategoryTechnologyFC BenefitCd/Crr/WtChangeCapital cost (RPE)Intro YearSalesPen.BaselineSection No.Improved controls - Aggressive Shift logic, early lock-up1.5 to 2.5% - $60 2010 - 4-speed automatic transmission 4.5.46-speed to 8-speed AT 2.7 to 4.1% - $500 to$1,650 2011 - 4-speed automatic transmission 4.5.4AMT 5.5 to 9.5% - $700 to $1,400 2011 - 4-speed automatic transmission 4.5.4Friction Reduction 0 to 1% - 0 to $500 Continuous - - 4.5.4TransmissionsLower Final Drive 2 to 3% - $- 2009 - - 4.5.410% Reduction in aero drag 2 to 3% 10% $60 to $120 Continuous - - 4.2.5Weight reduction via materials substitution, up to 2%0.6 to 0.9% per3% saved1 to 2% $1 to $2/lb 2012 - No weight reduction 4.4.7Materials substitution - Weight Reduction - 5%0.6 to 0.9% per3% saved2 to 5% $2 to $4/lb 2014 - incremental to 2% weight 4.4.7Load ReductionLow rolling resistance tires 1 to 2%- $6 to $9 2008 - Std singles 4.3.3.6Elec. Acc.2 to 4%-$500 to $2,0002014- - 4.1.6• Package 1: VVT and VVL - gasoline2.5 to 9% - $632 to $1,372 2010 - Gasoline, PFI, fixed valve 4.1.6• Package 2: SGDI, VVL and VVT - gasoline7 to 14% - $1,200 to $2,400 2012 - Gasoline, PFI, fixed valve 4.1.6• Package 3: Turbo-charged gasoline, down-sized engine; IncludesSGDI, VVLT11 to 17% - $2,500 to $3,600 2012 - Gasoline, PFI, fixed valve 4.1.6• Package 4: Diesel, turbo charged, HPCR (1,800 bar), NOxAdsorber or SCR19 to 24% +500 lbs $7,900 to $9,400 2010 50% Gasoline, PFI, fixed valve 4.1.6• Package 6: Improved Diesel - adopts higher FI, increased cylinderpressure, improved controls and turbo; similar to 2010-2012 HD tech4 to 5% - $1,000 to $2,000 2012 - Diesel Pkg 4 4.1.6Lean burn GDI 20 to29% - $3,250 to $4,3502014 - Gasoline, PFI, fixed valve 4.1.6EngineGasoline homogeneous charge compression ignition (HCCI) 20 to 27%- $3,185 to $4,285 2014 - Gasoline, PFI, fixed valve 4.1.6Parallel hybrid 15 to 20% 200 lbs$16.4 to $20.6K(High)$8.2 to $10.3K(Low)2012-2014 - No Hybrid 4.6.4.7HybridDual-mode or power-split hybrid 20 to 30% 250 lbs$12 to $17K (High)$24 to $34K (Low)2012-2014 - No Hybrid 4.6.4.73-243-25Table 3-10. Motor coach technology matrixCategoryTechnologyFC BenefitCd/Crr/WtChangeCapital cost (RPE)Intro YearSalesPen.BaselineSection No.2010 engine – 43.2 to 44.2% 4 to 5%+400 to 500 lbs$9.6 to $10.6K2010-2007-2008 15L engine4.1.4.12013 engine – 45.5 to 47.5% 9 to 12%+50 lbs$13.2 to $15.2K2013-2007-2008 15L engine4.1.4.22015 engine – 47.9 to 51.4% 13 to 18%+450 to 550 lbs$14.7 to $18.2K2015-2007-2008 15L engine—

Engine (11 to 13L)2020 engine – 47 to 51% 18 to 22%+600 to 800 lbs$21.4 to $25.9K2020-2007-2008 15L engine4.1.4.4Boat Tail4 to 6% 6.5 to 9% $1,500 to $2,000 2012-2014 - No aero features 4.2.4Streamlining - no cost estimate3 to 4% 6 to 8% $2,750 2012-2014 - No aero features 4.2.4

Bus AeroMotor Coach Aero Combination (boat tail + streamlining7 to 10% 13 to 15% $4,250 to $4,750 2014-2015 - No aero features 4.2.4Low Rolling Resistance Smartway Duals, tractor and trailer 1.4 to 2.1% 9% $30 per tire 2008 ? steel std duals4.3.3.2Low rolling resistance WBS Tires w/aluminum wheels + LRR duals 2.1 to 4.2% 19%$225 per wheel +tire2008 ~1% steel std duals4.3.3.2Next-generation dual 2.8 to 3.5% 15% $30per tire 2013 to 2015 — steel std duals4.3.3.2Next-generation WBS + LRR duals – Crr 0.00455.6 to 7.7% 33%$225 per wheel +tire2013 to 2015 — steel std duals4.3.3.2Tire monitor 0.42% $100 2008 ?5-10 PSI Underinflated4.3.3.2

Tires and WheelsATI0.42% $300 to $400 2008 ?5-10 PSI Underinflated4.3.3.2Automatic Manual Transmission4 to 8%+70 lbs -$10,0002008—6 speed AT 4.5.3Appropriate spec-ing: match the axles, transmission gears to theapplication1 to 3%——Pre-200860 to100%6 speed AT 0Increased Transmission Gears – 6 spd to 8 spd AT1.5 to 2%—$1,870 to $2,200 2010 ? 6 speed AT 0Reduced AT parasitics and friction1 to 1.5%—0 to $500 Continuous—6 speed AT 0

Transmission and DrivelineAggressive Shift Logic and Early Lockup1 to 2%—$100 2010—6 speed AT, Conventional shiftstrategy0WeightReduction0 to 1,000 lbs1,000 to 2,000 lbs2,000 to 3,500 lbs0.7%Per 1,000 lbs$2 to $4/lb$4 to $8/lb$8 to $10/lbContinuous—36K lb GVW4.4.4Parallel HEV Line-haul “Mild Hybrid":40 to 50 kW motor; Parallel,single motor and clutch7 to 10% 500 lbs $30 to $40K 2015 - No Hybrid 4.6.4.4Parallel Diesel HEV Transit Bus10 to 15% 1,000 to 2,000 lbs$180,000 to $220,000($36 to $44K w/80%subsidy)Available now ~5% No Hybrid 4.6.4.4

Hybrid PackagesGen II hybrid: Integration w/engine and after-treatment -- optimizeengine operation; implemented on either hybrid package2 to 3% -? - should be nominalcontrols upgrade2014-2015 - No Hybrid 4.6.4.44-1 4. Fuel Saving Technologies

This section provides detailed desc riptions of fuel saving technol ogies that are either available currently or will be in the near future (five to ten years). The fu el saving technologies are divided into one of several categories: engines and em issions, aerodynamics, tires and wheels, weight reduction, transmission and drivelin e, hybrid technologies, idle redu ction, and driver management and coaching. For each category, we describe the t echnologies, how they improve fuel efficiency, and the extent to which they apply to different vehicle classes and appli cations. Throughout this discussion, several different terms are used to refl ect different types of en ergy efficiency or fuel savings. These terms are defined as follows:
Fuel consumption (FC) benefit : The fuel saved, in terms of percentage by a given vehicle operating over a typical drive cycle (see Chapte r 2 for discussion of ve hicle and drive cycle assumptions). Peak Brake Thermal Efficiency : The thermodynamic efficiency of an engine operating at its most efficient point. The engine’s thermodynamic effici ency is defined as the energy out divided by the energy content of the fuel used. Drive Cycle Efficiency : The average brake thermal efficiency of an engine operating over a typical drive cycle for a gi ven application. 4.1 Engine and Emissions Technologies

4.1.1 Overview
Present-day medium- and heavy-duty trucks use both gasoline and diesel engines 6 . Diesel engines range in size from about 6 liters up to 16 liters. Gasoline engines lie primarily in the 5 to 8 liter range. This evaluation of medium-duty and heavy- duty engine technologies segments the engine market into three classes: “big bore” diesel engi nes (11 to 15L range); “m edium bore” diesels (6 to 9L range); and gasoline engines (5 to 8L). Th is segmentation is summarized in Table 4-1.

Table 4-1. Medium- and heavy-duty vehicle technology matrix assumptions

Engine In-Use Application 11 to 15L diesel engine Class 8 tractor trailer Refuse hauler Motor coach 6 to 9L diesel engine Class 3-6 box and bucket trucks Transit buses Class 2B pickups and vans 5 to 8L gasoline engines Class 2B pickups and vans

6 Some alternatively fueled engines ar e also used, including propane in medium-dut y trucks and natural gas in port trucks/pick up and delivery applications and transit buses. Electricity and hydrogen are also used in transit buses4-2 4.1.2 Diesel Engine Technologies
4.1.2.1 Approach
A key takeaway from discussions with engine manufacturers was that engines are complex systems that must be optimized as a whole. As su ch, it is difficult to assign discrete efficiency benefits to individual technologi es: some approaches directly increase fuel efficiency (e.g., reducing friction), while others are enablers for improving efficiency (e.g., improved engine controls allow combustion to occur closer to NO x limits). In addition, many strategies address similar problems in different ways: for example, energy from waste heat ma y be recovered either through a turbo-compounding system or from a bottoming cycle. Due to these complexities, evaluating engine technologies as a series of discrete options runs the risk of double counting.
To address this challenge, this evaluation of diesel engine technol ogies employs a top-down approach that identifies ther modynamic loss mechanisms and ot her engine losses. Individual technology strategies are then cate gorized according to the followi ng loss or waste heat recovery mechanisms:

• Heat transfer and exhaust

• Gas exchange

• Engine friction

• Parasitic engine loads and vehicle accessories

• Waste heat recovery 7

Characteristics of individual e ngine technologies were sourced from published specifications for current (2007 emissions-compliant) and 2010 engi nes, results of DOE- funded research by industry, publicly available reports, and data gathered during site visits.
Individual technologies were then collected into plausible pack ages, each associated with a specific market segment and timeframe. A packag e is defined as a collection of discrete technologies, which are associated with an estimat ed peak thermal efficiency and a “drive cycle” thermal efficiency (defined below). For example, an energy audit of a present-day diesel engine as shown in Figure 4-1, based on data furnished by engine manufacturers, was used to estimate the peak engine thermal efficiency for a base line 2007 emissions-compliant big-bore engine. A list of technologies that defi nes this 2007 engine was then compiled from the literature.

7 Waste heat recovery actually reduces exhaust gas losses, but because it functions separately from the engine itself, we have included it as a separate category.4-3 Indicated Closed Cycle Efficiency 50% Heat Transfer 26% Exhaust 24% Fuel Energy 100%

Gas Exchange 4% Friction 1.5% Accessories 2.5% Brake Power 42% Indicated Closed Cycle Efficiency 50% Heat Transfer 26% Exhaust 24% Fuel Energy 100%

Gas Exchange 4% Friction 1.5% Accessories 2.5% Brake Power 42%

Figure 4-1. 2007 diesel engine energy audit [Duggal 2009]

The estimated peak thermal efficiency of each package relies primarily on details from engine manufacturer technology roadmaps that were sh ared during site visits . Although diesel engine manufacturers differed in terms of precisely how they would meet various targets, they are in general agreement that improvements on the order of 20 percent are feasible in the next ten to fifteen years, with the potential to achieve p eak thermal efficiencies on the order of 51 to 53 percent for an advanced engine and up to 55 percent with waste heat recovery.
To construct engine packages associated with a specific time frame, TIAX extrapolated from the current engine status to the long- term target of 51 to 53 percent p eak thermal efficiency; and then assigned technologies to these pa ckages based on estimates of when specific technologies might come into the market. This technology road map draws largely on information furnished by Cummins during the committee’s site vis it [Cummins 2009a], which was supported by information offered to the committee during site vi sits. Figure 4-2 shows the current history of peak thermal efficiency for large bore engines and possible future improvements. Also shown on this figure is the history of the NO x and PM standards.
Incremental future engine efficiency improvement s are not corrected for the truck’s duty cycle. For example, improving the engine peak thermal e fficiency by 1 percent using a next-generation fuel injection system would improve the cycle thermal efficiency by 1 percent. For discrete technology packages – such as waste heat recovery systems – the data reflect estimates for fuel consumption reduction over a representative duty cycle.4-4 30% 35% 40% 45% 50% 55% 60% 65%

1985 1990 1995 2000 2005 2010 2015 2020 2025Brake Thermal Efficiency (%) BTE NOx Std PM Std 0.6

0.1

PM NOx Emission Std g/bhp-hr

6

4

2 0.3

0.2 0.4 0.5

NOx PM 10

8

Electronic Controls Turbo Eff Increasing Inj P; Cyl P EGR, VG Turbo

DPF SCR OBD, Controls Waste Heat Recovery Adv Engine Concepts, Vehicle Electrification

Figure 4-2. Past and possible future brake thermal efficiency improvements for large bore engines [Site Visits, Duggal 2009, Cummins 2009a]

To the extent possible, costs are estimated from direct references in the literature or data furnished on site visits. Because many of th e engine technology strategies entail continuous minor modifications and are implemented as a coll ective package when a new engine platform is introduced, in many cases, capital cost estimates are informed by past engine cost increases (from one generation engine to the next) and by soft estimates offere d during site visits. Published sources that are severa l years old often identify technol ogies and costs that are already widely deployed. In cases where these esti mates correspond to continuous improvement opportunities, capital costs from one generation engine to the next are considered to plausibly carry over.

Most of the literature and site visit discussi ons focused on the benefits, capital costs, and technical potential of the heavy- duty 11 to 15L diesel engines. As such, a number of assumptions were made to extend the results of the analysis to the 6 to 9L category. In general, it is assumed that a similar slate of engine efficiency techno logies can be applied to the smaller engines. However, the medium-duty diesel technologies a nd technology packages are differentiated from each other and their heavy-duty coun terparts in the following ways:

 Because the medium-duty applications tend to be lower mileage, there is less market pull for fuel efficiency. Therefore, in some cas es, it is assumed that continuously improving strategies (such as fuel system or cylinde r pressure) are one gene ration behind the heavyduty vehicles. Based on a review of engi ne manufacturer data for 2007 and 2010, this appears to be a reasonable assumption. Year4-5  Technology costs are scaled down to medium- duty on a case-by-case basis. Some fuel reduction strategies, such as friction reduction or engine controls, were judged to incur similar costs regardless of the system size; othe rs, such as aftertreatment, are expected to scale with engine size.

 Waste heat recovery systems are assumed to be a viable strategy only for vehicles that operate over high-speed, steady-st ate duty cycles. In practical terms, this means that waste heat recovery was only considered for li ne-haul and motor coach applications. It is also conceivable that electric turbo-compounding could be used in a series hybrid bus, for which the engine duty cycle co uld be near steady state.

4.1.2.2 Baseline Diesel Engine Description
Characteristics of the baseline medium- and big-bor e diesel engines are ba sed on a review of the technologies that are available in 2007 emissions-c ompliant engines for the two different engine classes. These characteristics are summarized in Table 4-2. A detailed table summarizing all of the engines that were reviewed is included in Table 4-3 and Table 4-4.

Table 4-2. Baseline characteristics for 2007 medium- and big-bore diesel engines
Engine Technologies 11 to 15L 6 to 9L

Cylinder pressure 190-200 Bar 170-180 BarFuel Injection 1800 to 2200 bar common rail -or33K psi unit injector Multiple injections per cycle 1600 to 1800 bar common rail

NO x Control Cooled medium rate EGR, DPF Cooled medium rate EGR, DPF
Particulate Control DPF w/ac tive regen DPF w/active regen Aspiration Variable geometry turbo charger Variable geometry turbo charger Engine Controls Open-loop Open-loop Low-speed idle Yes Yes Waste-heat recovery None None
Accessories 8 Belt-driven mechanical 1 to 5 kW Belt-driven mechanical 1 to 5 kW, except bus – 30 to 40 kW Weight 2,200 to 3,100 lbs 1,100 to 1,700 lbs

8 Accessory load estimates from 21 st Century Truck [DOE 2000]4-6Table 4-3. 2008 and 2010 11 to 15L sample heavy-duty diesel engine specificationsaSize (L)Engine HPTorque(ft-lb)Wt(lb)CR Turbo Machinery Fuel InjectionEmissionsOther2007-Compliant 11 to 15L Engines14L DD Series 60 445-515 1450-1650 2557 17:1 Elec. VG TurboDual solenoid electronic unitinjectors ~2000 Bar, multiinjectionsMed EGR,DPF11-15LCummins ISXCummins ISM385-600280-425145-18501150-15503,0212,268?Electronically actuated VGTurboUnit InjectionMed EGR,DPFDOHC, Multi-torque,Load Based speedcontrol11-13LMaxxForce 13MaxxForce 11410-475330-3901450-17001250-14002,2442,24417:117:1Twin series turbochargers;Air/Liquid IntercoolerCommon rail, 1800 Bar, multinjections/cycleMed EGR,DPFOHV11-16LVolvo D16Volvo D11450-600325-4051650-20501250-14503,0912,24616:1Sliding nozzle VGElectronically Actuated turbo35,000 PSI Dual SolenoidUnit InjectorMed EGR,DPFSOHC12.8L DD MBE4000 350-450 1250-1650 2270 18:1 Wastegated turbo2000 Bar Unit injector(SMART Fuel System), multiinjection, rate shapingMed EGR,DPF2010-Compliant 11 to 15L Engines11-16LVolvo D16Volvo D11450-600325-4051650-20501250-14503,0912,24616:1Sliding nozzle VGElectronically Actuated turbo35,000 PSI (2400 Bar) DualSolenoid Unit InjectorSCR, LowEGR, DPFSOHC11L-15L Cummins ISX400-600310-4251450-20501150-16503,1862,812?Sliding nozzle VGElectronically Actuated turbo2,200 Bar common rail XPIFuel System – multipleinjections per cycleSCR, LowEGR, DPF5% FC improvement;SOHC, Gear-downprotection11/13LMaxxForce 13MaxxForce 11410-475330-3901450-17001250-14502,4002,40017:116.5:1Dual stage turbocharger,Intercooler & Aftercooler2,200 bar common rail, multinjections/cycleMassiveEGR, DPFOHV15L DD15 455-560 1550-1850 2880 18.4:1Mechanical TurboCompound & Non-VG Turbo2,100 Bar; AmplifiedCommon Rail Fuel System(ACRS), variable rateshapes, multi injections/cycleSCR, LowEGR, DPF5% FC improvement;Multi-torque engine;DOHC;aCummins 2009b, Cummins 2009c, DetroitDiesel 2009a, Detroit Diesel 2009c, Detroit Diesel 2009d, Volvo 2009a, Volvo 2009b, MaxxForce 2009, Sturgess 20074-7Table 4-4. 2008 and 2010 6-9L heavy-duty diesel engine specificationsSize (L)HPTorque(ft-lb)Wt(lb)CRTurboMachineryFuel Injection Emissions2007-Compliant 6 to 9L Diesel Engines6.7-9Cummins ISLCummins ISB345-365200-3251150-1250520-7501,6851,190?Sliding nozzle VGElectronicallyActuated turbo1800 Bar High pressurecommon rail, multiinjection/cycleMed EGR, DPF9.3 MaxxForce 10 310-350 1050-1150 1,560 ? TurbochargedElectro-hydraulic fuelsystem - 1600 BarMed EGR, DPF6.4 MaxxForce 7 200-230 560-620 1,160 17.5:1Elec. Turbochargerw/charge air coolerElectro-hydraulic fuelsystem - 1600 BarMed EGR, DPF7.2L DD MBE900 190-250 520-660 1,392 18:1 Wastegated turbo~1,800 Bar Unit injector(SMART Fuel System),multi injection, rateshapingMed EGR, DPF2010-Compliant 6 to 9L Diesel Engines9 Cummins ISL 345-380 1150-1300 1,850 ?Sliding nozzle VGElectronicallyActuated turbo2,200 Bar common railXPI Fuel System –multiple injections percycleSCR, LowEGR, DPF6.7 Cummins ISB 200-325 520-750 1,340 ?Sliding nozzle VGElectronicallyActuated turbo1800 Bar common rail fuelSystem – multipleinjections per cycleSCR, LowEGR, DPF9.3 MaxxForce 10 310-350 1050-1150 1,425 17.2:1Dual stageturbocharger,Intercooler &Aftercooler1900 Bar Electrohydraulic high pressureMassive EGR,DPF6.4 MaxxForce 7 220-300 560-660 1,225 16.7:1Regulated dualstage turbochargerw/intercooling1900 Bar Electrohydraulic high pressureMassive EGR,DPF4-8 The baseline engine efficiency assumptions are based on two parameters:
1.) What is the engine size? Big bore engines are assumed to have adopted the most advanced technology and therefore have hi gher peak thermal efficiency.
2.) Is the duty cycle dominated by urban (stop-and-go) or highway driving? Engines spend more time operating outside the optimum efficiency regime during stop-and-go (and hence have a greater spread between peak thermal effi ciency and cycle thermal efficiency).
Table 4-5 shows the assumptions used for the applications un der consideration.

Table 4-5. Baseline engine efficiency assumptions [Site Visits, DOE 2000, NHTSA 2009]

Application Engine Size Duty Cycle η Peak (2007compliant) η Cycle (2007 compliant) Tractor Trailer 11 to 15L Highway 41 to 42% 38 to 39%
Refuse 11 to 15L Urban 41 to 42% 34 to 37%
Box truck 6 to 9L Urban 40 to 41% 31 to 35%
Bucket truck 6 to 9L Urban 40 to 41% 31 to 35%
Transit bus 6 to 9L Urban 40 to 41% 34 to 37% Motor coach 11 to 15L Highway 41 to 42% 36 to 38% Pickup and Van (Diesel) 6-9L Mix 40 to 41% 30 to 35% Pickup and Van (Gas) 5-8L Mix 33 to 36% 20 to 25%

4.1.3 Diesel Engine Technology Descriptions
A brief description of individual strategies for improving the effi ciency of diesel engines beyond the 2007-compliant baseline is included below.
4.1.3.1 Emissions Systems
Table 4-6 shows our assumptions regarding fu ture technologies to meet the upcoming 2010 emission standards. Included are estimates of fuel consumptions effect, capital costs, and year of introduction.
Improving the efficiency of heavy-duty diesel engines entails a complex tradeoff between minimizing particulate and NO x emissions and maximizing fuel efficiency. While higher engine efficiency leads to lower fuel use and re duces particulates, it leads to higher NO x levels. Optimizing these tradeoffs requires tightly c oupled integration between the engine, the aftertreatment, and controls. This process include s adjusting a number ofdifferent engine subsystems in parallel. Although technically not a “fuel efficiency” strategy, modern emissions systems are tightly integrated with the engine, and much of the engine design challenge revolves around managing the tradeoffs between NO x and fuel efficiency.4-9 Table 4-6. Emissions strategies
Technology % FC Benefit Capital cost Intro SCR w/Low-rate EGR 3 to 6 (incl. DEF penalty) $9,000 to $10,000 (11 to 15L) $7,000 to $8,000 (6 to 9L) 2010

High-rate EGR -1 to -2 $8,000 (11 to 15L) $6,000 (6 to 9L) 2010
High-rate EGR w/Mixed Mode Combustion 1 to 2 $10,000 (11 to 15L) $8,000 (6 to 9L) 2012

Two different emissions pathways are summarized in the technology matrix: an in-cylinder only pathway, and an in-cylinder system coupled with SCR aftertreatment pathway. Lean NO x adsorbers offer yet another option in pl ace of SCR, but these were not included 9 . Although both an SCR and in-cylinder only emissions pathways were characterized, the engine technology packages assume that the in-cylinder SCR pathway is adopted, as this appears to be the industry trend.
Selective Catalytic NO x Reduction
Selective catalytic reduction (SCR) combin ed with EGR will be introduced on most 2010 engines to meet the new EPA NO x standards. Because SCR is a highly effective aftertreatment approach, its introduction will enable engines to be optimized to maximize fuel efficiency, rather than minimize engine-out NO x . Based on information gathered during site visits and company literature, 2010 SCR systems are estimated to improve engine efficien cy by approximately 4- 5 percent compared to a 2007 in-cylinder EG R-based emissions system [Site Visits, factsaboutscr.com] and by an even greater percen tage compared to 2010 in-cylinder approaches [Stanton 2008]. This 4-5 percent in crease in engine efficiency is offset by the use of diesel emission fluid (DEF) in the SCR system. The vo lume of DEF use is about 2 percent that of diesel fuel used. Assuming DEF is priced the same as diesel, this 2 percent should then be subtracted from the engine benefit of 4-5 pe rcent giving a net efficiency improvement of 2-3 percent for the 2010 SCR engines. As more effective low-temperature catalysts are developed, the NO x conversion efficiency of the SCR syst em will increase. Next-generation SCR systems could then enable still further efficiency improvements; alternatively, these advances could be used to maintain efficiency while down- sizing the after-treatment. It was suggested that continued optimization of the catalyst could offer 1 to 2 percent additional reduction in fuel use [Site Visits].
The chief drawbacks of an SCR emissions system are its higher capital cost and the added cost and inconvenience of maintaining diesel emissions fluid (DEF) levels, which is integral to the NO x reduction process. Volvo has announced that their SCR system will incur a surcharge of $9,600 on their large bore (11 to 16L) engines [McN amara 2009], and this cost will include the

9 Although NOx adsorbers are being considered for light-duty diesels and were used in some MD 2007 engines, they are being phased out of the medium- and heavy-duty segmen ts. This is due to a combination of high cost, sensitivity to sulfur poisoning, and adverse fuel efficiency impacts.4-10 SCR catalyst, DEF storage and injection system, and controls. Daimler has announced that their system will range from $7,000 (for their smaller, 6 to 9L engines) to $9,000 (for their larger 11 to 15L offerings) [LMT 2009]. We have assu med an SCR cost of $7,000 to $8,000 for 6 to 9L engines and $9,000 to $10,000 for 11 to 15L engines.
DEF consumption is expected to be about 2 percent of diesel c onsumption and cost on the order of $2.75 per gallon [truthaboutscr.co m]. For a line-haul truck, th is would incur an additional annual operating cost of approximately $1,100 per year (assuming 120,000 miles and 6 MPG). Note we have included this cost in our estima tes of efficiency improvements assuming that DEF costs are the same as diesel. If DEF costs are lower, as might be expected in large volume dispensing, then the SCR efficienci es would be slightly higher.

Diesel Particulate Filters
Diesel particulate filters (DPFs ) are standard on all 2007 emissions-compliant diesel engines. The 2007 DPF systems degrade fuel efficiency du e to higher back-pressure on the engine, which increases pumping losses, and since they requ ire occasional “active” regeneration, in which a small amount of fuel is burned to assist in particulate filter regeneration. Beginning with the introduction of 2010 SCR-equipped engines, whic h will have lower engine-out particulates (enabled by less EGR), information furnished during site visits suggests that the need for active regeneration will be much lower, and back-pressure will be reduced. With these changes, DPFs are likely to decrease from a 1.5 to 2 percent fuel consumption penalty to signifi cantly less than 0.5 percent [Site Visits, truthabou tscr.com, Volvo 2009a, Duleep 2008]. 10

In-Cylinder Approach
An in-cylinder emissions approach is primarily a low-cost emissions enabler – not a fuel efficiency enabler. The proposed in-cy linder emissions pathway to meet 2010 NO x standards uses high-rate cooled EGR and makes use of advanced low-temperature combustion concepts such as homogeneous or premixed charge compre ssion ignition (PCCI or HCCI) not only in the low load-speed operating conditions but also in the high load-speed operating conditions. This approach offers lower initial costs than SCR a nd does not require any additional operating cost (SCR users must periodically replenish DEF leve ls for proper operation) but does not allow for higher engine out NO x and lower fuel consumption. Navist ar is currently the only manufacturer that has committed to this approach for their 2010 engines. 11 Navistar has announced that the incremental cost of their high -rate EGR system is $6,000 for smaller (6 to 9L) engines and $8,000 for their larger (11 to 13L) engines [Transport Topics 2009].
While 2010 SCR-based systems will reduce fuel consumption by approximately 3 percent compared to 2007 engines, it is likely that th e higher rate EGR needed to approach the 2010 NO x limits will degrade system efficiency still further (perhaps 1 to 2 percent). A few strategies exist to reduce these EGR-related losses, such as us ing an EGR cooler or an EGR pump; these are

10 Note that this improvement pre-supposes an SCR-based after- treatment system, which is being pursued by all of the OEMs except for Navistar.

11 Navistar will be using NOx emission credits to offset their higher NOx emissions of 0.5 g/bhp- hr in order to meet the standar d of 0.2 g/bhp-hr.4-11 described in the section on gas-exchange losses. However, they do not come close to the fuel savings offered by SCR.
Achieving 2010 NO x levels using high rate EGR will likely require an advanced combustion technology such as HCCI. Implementation entails a dditional technologies such as variable valve actuation (VVA), a start of combustion sensors, and a dual-staged turbocharger to achieve 2010 emissions levels. These advanced combustion co ncepts are expected to offer a minor fuel efficiency benefit compared to high rate EGR – 1 to 2 percent – at an incremental cost on the order of $2,000.

4.1.3.2 Heat Transfer and Exhaust Losses

Table 4-7 summarizes our estimates of fuel c onsumption benefits and capital costs for fuel injection, controls, and combustion systems.

Table 4-7. Strategies to reduce heat transfer and exhaust losses
Technology % FC Benefit Capital cost Intro Fuel Injection Systems 1 to 4 0 to $500 Continuous Controls 1 to 4 $60 to $150 Continuous Combustion 1 to 3 $500 to $1,500 Continuous

Fuel injection Systems
Finely controlled, high pressure fu el injection is a key enabler fo r more efficient combustion and a cleaner, more consistent fuel burn. Current state-of-the-art system s that are planned for deployment in 2010 engines include high pressu re (2000 to 2,400 bar) common rail injection systems with advanced nozzle designs that are capa ble of finely shaped a nd controlled spray with multiple injection events per cycle [Cum mins 2009b, MaxxForce 2009, Detroit Diesel 2009a]; they also include high pressu re unit injectors [Volvo 2009a].
Potential future improvements will continue to improve spray control, allow more accurate timing of injection with combustion events, a nd increase fuel injection pressure. Improved material properties and controls could enable pressures of up to 3,000 bar in the 2015 timeframe and perhaps 4,000 bar by 2020. Future systems w ill also utilize increasingly sophisticated injection techniques such as variab le spray nozzles, piezo-e lectric injectors, or super-critical fuel injection 12 . These advances are possible in the 2013 to 2015 timeframe [Site Visits, Cummins 2009a]. Fuel injection systems were estimated on site visits to offer between 1 and 4 percent improvement in fuel efficiency. These estimate s are lower than other information found in the literature; for example, Vyas [2002] estimates fuel injection systems have the potential to improve efficiency by 6 percent, and this estimat e has been widely propag ated (e.g., Frey [2007] and EIA [2009]). However, it is not clear what the baseline system to which this efficiency

12 Refers to fuel changing instantaneously from liquid st ate to super critical gaseous state at injection.4-12 increment refers; as these studies are several year s old, it is likely that the envisioned changes have already been adopted. As such, we have used the more conservative estimate.
Because fuel injection systems are tightly inte grated with the design of the overall engine platform, and because they are undergoing contin uous incremental modification, it is difficult to identify an exact cost. Vyas [2002] projects that an improved fuel injection system costs on the order of $500. Discussions during site visits suppor ted this estimate: historically, advanced fuel injection approaches have come at a minor incr emental cost and may even be cost neutral once economies of scale are fully realized. As such, we estimate fuel injection system costs to range from $0 to $500.

Engine Controls
Advanced engine controls will be enabled in pa rt by the onboard diagnostic systems that will be mandated for medium- and heavy-duty trucks, beginning in 2010 and becoming fully phased in by 2013. Increasingly sophisticated engine controls – particular ly a transition to closed-loop controls approaches – enable engine efficiency improvements. Closed loop controls will feed information about the engine’s operating regime a nd emissions back to the system controls. This improved feedback will allow manufacturers to optimize emissions and fuel savings across a variety of operating conditions. Duri ng site visits, the benefits of improved engine controls were estimated to range from 1 to 4 percent. Simila r results are reported by Zh ang [2008] as part of DOE-funded research by Detroit Diesel. However, this number should be regarded with caution as improved engine controls really acts as an enabler for other improvements.
In addition to the required software changes, onboard diagnostic syst ems (OBDs) and closedloop controls will require NO x sensors. In the EPA final notice of rulemaking on onboard diagnostics, the total cost of the hardware is estimated at$43 (2010 to 2012) to $57 to $60 (post2012). When non-recurring engineering costs are included, the cost of an OBD system is estimated at between $100 and $155; these highe r costs are only incurred during years when development is most active (i.e., 2010 to 2012, and when new engine platforms are introduced in later years). The EPA estimates include only upgrad es to the vehicle computer and the required algorithm development; they assume that NO x sensors are already implemented as part of other emissions control [EPA 2008a]. Based on the EPA’ s analysis, the cost of advanced engine controls is estimated to range in cost from $60 to $150. It should be noted these costs could be significantly higher if NOx sensors ar e not already incorporated into existing emissions control.
Combustion Chamber Design/Increase Cylinder Pressure
Improved combustion chamber design allows for improved air management and mixing and improved materials that enable higher cylinder pressures. These enhancements allow a more complete burn of fuel and higher combustion temperatures, both of which improve engine thermal efficiency. Combustion chamber design enhancements will require more advanced materials and a more complex machining process. In addition, because higher cylinder pressures lead to higher temperature combustion – which fosters NO x formation – these higher pressures must be accompanied by concomitant reductions in NO x via other approaches, such as improved NO x conversion efficiency by the system aftertreat ment, advanced fuel injection techniques, and4-13 improved engine controls. The fuel consumption be nefit of these improvements is estimated at 1 to 3 percent.
Vyas [2002] estimates that in creased cylinder pre ssure incur an incremental cost of $500. However, during discussions on site visits, it was suggested that this estimate might understate the cost; other information in the literature estimates $2,200 for these types of improvements plus advanced fuel injection [Global Insi ght 2004]. Combustion chamber improvements will entail new, potentially more expensive materi als, and, as designs become more complex or materials harder to work with, are likely to be accompanied by increasing machining costs. Based on this feedback, we have estimat ed a range of costs from $500 up to $1,500.

4.1.3.3 Reduce Gas Exchange Losses and Improve Air Handling
For EGR flow to occur from the engine exhaust to the engine intake, the exhaust pressure needs to be higher than intake pressure. Th is condition, known as negative delta p (- ∆ p), degrades the efficiency of the turbocharger, which pref ers a high pressure intake [NESCCAF 2009]. A number of approaches exist that can help reduce these “gas exchange” losses (also called “air handling” losses). These techniques offer benefits on high-rate EG R emissions system, as well as SCR-based systems. Table 4-8 summarizes syst ems that could reduce gas exchange loses.

Table 4-8. Strategies to reduce gas exchange loss
Technology % FC Benefit Capital cost Intro Advanced EGR 1 to 1.5 $750 2010Turbocharging (improved efficiency, dualstage, e-turbo) 1 to 2 $0 to $1,000 Continuous

VVA 1 $300 2012

Advanced EGR Approaches
An improved EGR system can reduce the efficien cy penalty due to EGR in several ways. One approach uses an EGR pump to drive exhaust gas from the exhaust to the intake, rather than the passive flow mechanism that is currently used. Such a system allows the engine intake to remain at higher pressure (overcoming the pressure dr op condition described abov e), which allows for more effective and efficient turbocharging. This improved efficiency n eeds to be balanced against the increased parasitic load of the pump, as well as the added cost.
Another approach to reduce the fuel efficiency penalty of EGR systems entails cooling EGR gases (beyond the cooling level offered by pr esent-day cooled EGR systems). Lowering the temperature of the charge in the engine reduces NO x formation, which then allows an advance in engine timing, thereby increasing the engine’s average thermal e fficiency. Such a system would require an additional EGR cooler. The capital cost and efficiency of this system were estimated as part of the NESCCAF/ICCT study at $750 an d 1.2 percent, respectively [NESCCAF 2009].4-14 Turbocharger Improvements
All of the diesel engines currently sold in th e medium- and heavy-duty market are turbocharged; of these, most use a variable geometry de sign. Turbochargers can enhance engine thermal efficiency beyond the level offered by current designs by improving the efficiency of the turbocharger itself; by boosting the engine intake pressure; or by reducing the turbocharger system response time, which allows the engine to operate in higher efficiency regimes at low loads. Improved response time is particularly bene ficial for stop-and-go duty cycles, in which the engine spends more time operating in a part-load condition.
Turbocharger efficiency is a f unction of compressor and turbine de sign, both of which are likely to benefit from continuous minor enhancements. Strategies for improving response time include dual-stage turbochargers, or us ing electronically actuated single -stage turbos. Approaches for boosting intake pressure include electrically or hydraulical ly assisted turbocharging.
Enhanced turbocharger improvements are estimated to come at an incremental cost that ranges from cost-neutral to $1,000 and could offer up to 2 percent reduction in fuel consumption. The estimates of fuel savings are based primarily on fee dback from site visits. As another data point, Walsh cites improvements ranging from 2.5 to 4.5 per cent, but it is unclear what the baseline for this estimate is; Kruiswyk [2008] reports that similar benefits (3.7%) were demonstrated by Caterpillar as part of DOE-funded research. Th ese benefits arise from improved turbocharger efficiency. Capital costs are based on TIAX estimat es that were subsequently reviewed during the site visits. The nominal logic is that th e cost of the above pr oposed enhancements are bracketed on the low-end by turbocharger effici ency improvement and at the high-end by the dual-stage turbocharging system, which would repl ace one larger turbocharger with two smaller units. Frey [2007] estimates the cost of a turboc harger for medium and heavy-duty trucks at $700 to $1,000; Global Insights/TIAX [2004] estim ates $1,700 for a large turbo-compound unit. Because this technology requires a smaller unit, we have used the lower cost estimate.
Variable Valve Actuation (VVA)
As a standalone system, variable valve actua tion (VVA) can offer efficiency improvements on the order of 1 percent [NESCCAF 2009] by allowing the turbocharg er to operate at its most efficient point. However, it also acts as an en abler for other technology st rategies. These include mixed mode combustion or HCCI, for which it helps precisely control combustion events and waste-heat recovery, for which it can be used to maximize the energy remaining in the exhaust [Gutterman 2008]. The incremental cost of VVA was estimated at $300, based on estimates from NESCCAF [2009]; this estimate is in close agreemen t to that estimated for the cost of variable valve lift and timing in gasoline engines fr om the NHTSA light-duty study ($400 to $600) [NHTSA 2009].

4.1.3.4 Friction Reduction

There are a number of low-cost opportunities to reduce engine friction. These include using advanced lubricants (synthetics, perhaps vapor -phase long term), improved bearings, and other minor modifications in moving parts within the engine (piston/cy linder, etc). Based on information gathered during site visits, total th ermodynamic losses due to friction were estimated4-15 to reduce engine thermal efficiency from 1.5 to 2.5 percent. 13 Using a combination of strategies, manufacturers were in general agreement that reducing engine friction could reduce fuel consumption by at least 1 percent and potenti ally up to 2 percent. The cost for these improvements ranges from minimal cost (~$0) for changes such as synthetic lubricants to $500 for a full combination of design changes. In the light-duty rulemaking, some of the more costly approaches identified for reducing friction in clude improved material coatings, materials substitution, and thermal manage ment [NHTSA 2009]. Frey [2007] estimates the cost of friction reduction at $500; NHTSA uses a range of $5 to $392 for large trucks. The NHTSA estimates scale according to the number of cylinders; they include estimates for gasoline engines that have up to 8 cylinders. We have used a range of $0 to $500 as shown in Table 4-9.

Table 4-9. Friction reduction strategies
Technology % FC Benefit Capital cost Intro

Friction Reduction (lubricants, bearings, materials, coatings, etc) 1 to 2 $0 to $500 Continuous

4.1.3.5 Parasitic Engine Loads and Accessories

Parasitic loads include accessories needed to run the engine or provide power to vehicle systems, such as cooling fans, the alternator, actuators, power steering pumps, air brake compressors, water pumps, and fuel pumps and creature-comfort loads such as the air conditioning compressor, ventilation, and heating system. In current vehicles, parasitic loads are primarily mechanically driven off the engine.
Parasitic loads may be reduced by either improving the efficiency of mechanical systems – such as by using variable displacement pumps – or by switching to electric accessories. Electric accessories are advantageous because they can be operated on an as-needed basis – independent of the engine operation – and can be inherently more efficient th an their mechanical counterparts over a wider range of operating c onditions. They also a llow the engine to be shut down during idling.
Currently, accessory electrificat ion is primarily considered as a component of a broader electrification stra tegy, such as hybridization or electric waste-heat recovery. 14 This is because electric accessories require higher voltage el ectric systems and may require additional energy storage beyond that which is currently deployed on mechanical systems. In addition, due to low production volumes, unit prices remain high. When implemented as part of a broader electrification package, a ccessory electrification is both lower co st and more beneficial than as a standalone approach. Hybrid systems and electr ic waste heat recovery already include the tertiary system upgrades identified above (h igher voltages and increased energy storage).

13 One company lumped friction and parasitic losses together at 5 percent. We have interpreted these results to suggest that parasitic losses contribute 2.5 percent and friction losses contribute 2.5 percent.

14 This includes electric turbo-compoundi ng, a Rankine cycle coupled to a generator, and thermo-electric waste heat recovery.4-16 Moreover, electrified accessories offer a ready demand for electric power that is generated by waste heat recovery or regenera tive braking. Direct util ization of this rec overed electric energy (as distinguished from conversion to mechanical power) will be more efficient. These systems can also enable full, mild, or start-stop hybrids to shut the engine-off at idle. This would offer minor benefit on long-haul routes but significant fuel savings in the city. If hybrid production volumes increase, thereby reducing the cost of el ectric accessories, accessory electrification may become a more viable fuel consum ption reduction strategy on its own.
Frey estimates an incremental cost of $500. Howeve r, we received feedback from reviewers that these costs were far too low for today’s low volume production. Based on this feedback, in the near-term, electrifying accessories is estim ated to add $1,000 to $2,000 incremental cost. As production volumes increase, this incremental cost could reduce to $500 to $1,000 – near the levels seen in the light-duty se ctor [NHTSA 2009]. The fuel cons umption benefit of electrified accessories has been estimated to range anywhere from 1 to 5 percent [Lane 2009, Site Visits, NESCCAF 2009, Greszler 2006]. Most sources tend to fall in the range from 1 to 3%, so we have used the lower end of these estimates.
Based on feedback received during s ite visits, we estimate that mechanical systems with variable displacement pumps can reduce fuel consumption by 1 to 2 percent, at an incremental cost of $200 to $500.

Table 4-10 summarizes the Parasi tic Engine Loads and Accessories benefits and capital costs.

Table 4-10. Parasitic load reduction strategies
Technology % FC Benefit Capital cost Intro Variable Displacement Pumps 1 to 2 $200 to $500 2010

Accessory Electrification 1 to 3 $1,000 to $2000 (low volume) $500 to $1,000 (High volume) 2012

4.1.3.6 Waste Heat Recovery
Table 4-11 shows several technologies to recover engine waste heat.

Table 4-11. Waste heat recovery strategies
Technology % FC Benefit Capital cost Intro Mechanical Turbo-compound 2.5 to 3 $2,000 to $3,000 2010 Electrical Turbo-compound 4 to 5 $6,000 to $7,000 ($3,000 to $4,000 w/Hybrid) 2013

Bottoming Cycle 6 to 10 $7,200 to $15,100 20154-17 Waste heat recovery systems o ffer the opportunity to reduce the fuel consumption of highway vehicles by up to 10 percent. Because they rely on recovering energy from the exhaust, waste heat recovery has the most promise for line-haul duty cycles or other appl ications that entail extended periods operating the engine at high lo ad. For the purposes of this study, we have considered waste heat recovery for line-hau l and motor coach applications. A number of different approaches to waste he at recovery are being considere d. These include mechanical and electrical turbo-compound systems, thermo-el ectric or thermo-acoustic devices, and bottoming cycles.
Mechanical Turbo-Compound
A mechanical turbo-compound system uses hot e xhaust gas to drive a small gas turbine. The turbine is coupled to the engine shaft, ther eby supplementing the engine’s power output. Mechanical turbo-compound systems are just co ming to market: a mechanical turbo-compound system is implemented on Detroit Diesel’s 2008 DD15 engine; other manufacturers have not yet implemented this strategy on their engines. At peak load, the system offers 50 additional horsepower as indicated in Figure 4-3 [Heil 2009].

Figure 4-3. Detroit Diesel Mechanical turbo-compound system [Detroit Diesel 2009a]

A similar mechanical turbo-compounding system was modeled as part of the NESCCAF/ICCT [2009] study and found to reduce fuel consum ption by 2.5 to 3 percent; Duleep [2008] and information furnished on site visits also suggest benefits on the order of 3 percent. Other sources estimate the benefit of turbo-compounding as hi gh as 4 to 5 percent [Kruiswyk 2008, Kruiswyk 2006]. We have chosen to use th e lower range estimates (2.5 to 3 percent), as these estimates are based on verifiable, real-world results (drive-c ycle modeling, as in the case of NESCCAF/ICCT and on-road testing, as in th e case of Detroit Diesel).4-18 NESCCAF/ICCT estimates the capital costs of a mechanical turbo-compounding at $2,650 but with some uncertainty due to variations as to how different manufacturers would implement such a system and as to which design modifications are already included in current designs. These estimates are based on bottom-up estimates of the design modifications needed to implement the system, which include port-liners to help retain thermal energy in the exhaust, VVA, and a power turbine. Including the cost un certainty gives a range from $1,900 to $3,500; Duleep [2008] estimates costs as high as $5,000.
Although Detroit Diesel has not published data as to the cost of their system, the up-charge from a Series 60 engine to their new DD15 engine is $2,500 [Merrill 2009]. The bulk of this price increase is likely due to the addition of a mechanical turbo-com pounding system, although the new engine does include additiona l design enhancements (notably, an advanced fuel injection system). This data point would suggest that the addition of the mechanical turbo-compounding system adds between $2,000 and $2,300 to the engine price. This estimate should also be treated with caution, as manufacturer pric ing strategies may not reflect the actual incremental cost of the technology – particularly during initial product introduction when economies of scale have not been fully realized.
Based on NESCCAF report and information on the DD15 engine, we have estimated the capital cost of a mechanical turbo-compounding syst em to range from $2,000 to $3,000, and offer a 2.5 to 3 percent fuel consumption reduction over a highw ay duty cycle. Given that the benefits of a turbo-compounding system depend on high-load, st eady state operating conditions, we have not included it in the medium bore technology pathway.
Electric Turbo-Compound
A mechanical turbo-compounding system can be enha nced by coupling the turb ine to an electric generator – thereby converting engine waste heat into electric power. This surplus power can be used to charge batteries (for later use), power electric accessories, or instantaneously supplement engine power. Its primary advantage compared to a mechanical system is that it decouples the waste heat recovery apparatus from the engine, allowing supplemental power to be used when it is most advantageous.
In addition to the components required to im plement a mechanical turbo-compounding system, an electric turbo-compounding system requires: an energy storage system; a generator that couples to the energy recovery turbine; an additio nal motor/generator that couples to the engine crankshaft; electric accessories; and a power electronics/control sy stem. A schematic of a typical system is shown in Figure 4-4.
SwRI modeled a 40 kW electric turbo-compound as part of the NESCCAF/ICCT work [2009] and estimated benefits at 4.2 percent, including el ectrification of accessories. Caterpillar, as part of DOE-funded work, modeled a system (Figure 4-4) that showed 3 to 5 percent improvement [Kruiswyk 2005], while John Deere i nvestigated a system (off-hi ghway) that offered 10 percent improvement [Vuk 2006]; it is unclear if this estim ate represents a single point (peak) benefit or was meant to reflect operation under real-world conditions. None of these systems has been demonstrated commercially. Due to the greate r certainty surrounding th e Caterpillar and4-19 Figure 4-4. Electric turbo-compound design schematic [Kruiswyk 2005]

NESCCAF estimates, we have used a range of 4 to 5 percent for our estimate. This includes the benefits of electric accessories.

The costs of the electric turbo- compounding system have not been well-characterized in the literature. TIAX, as part of the NESCCAF/I CCT [2009] study estimated costs at $6,550, which includes the elements of a mechanical turbo-co mpounding system, plus the addition of electrical motors, controllers, and accessories. The J ohn Deere work estimated $50/kW at mature production volumes, but it is not clear what this syst em includes, nor is it cl ear if this refers to capital cost or a retail price eq uivalent (RPE). As such, we have used the TIAX cost estimate, adjusted to reflect the uncertainty in the co st of a mechanical turbo-compounding system – $6,000 to $7,000.
An electric turbo-compound is most attractive when implemented as part an overall vehicle electrification stra tegy. This is because a number of system components overlap with those that go into a hybrid. In a hybrid vehicle, an electric turbo-compounding system could be implemented with the marginal addition of a me chanical turbo-compound plus a small electric generator. The costs of such an electric turbo-compounding system incremental to a hybrid vehicle would then range from $3,000 to $4,000.
Bottoming Cycle
A number of approaches have been proposed to implement a Rankine bottoming cycle. These vary depending on the working flui d that is used (steam vs. orga nic), the output (electrical vs. mechanical), and the size of the system. In genera l, the system costs and benefits vary depending on system size, as well as if output is electri cal or mechanical. Discussions with manufacturers suggested that they envision the bottoming cycle as a promising t echnology that could come into the market in the 2015 timeframe. However, it is s till in the early stages of development, and there are significant capital cost and packaging issues to be resolved. They view the bottoming4-20 cycle as a bolt-on engine option, as distinguished from a package th at is tightly integrated with the engine.
NESCCAF/ICCT [2009] modeled a full-sized el ectric steam bottoming cycle. The modeled system was sized to capture waste heat at peak load (57 kW). However, later analysis suggested that most of the benefits coul d be realized using a smaller, lower cost system. As such, two smaller size systems were costed, and the fuel co nsumption benefit of these smaller systems was estimated using spreadsheet analysis. System co sts were estimated from bottom-up analysis of the components that would be used to build such a system. The final results of the NESCCAF/ICCT study estimated the following cap ital costs and benefits for three different bottoming cycle systems:

• 57 kW – 10 percent reduc tion in fuel use, $23,800

• 32 kW system – 8 percent reduction in fuel use, $15,100

• 12 kW system – 6 percent reduction in fuel use, $8,400
System weight, again based on the components used to build the system, was estimated at 240 lbs.
Information gathered from the literature and duri ng site visits shows a similar range of fuel consumption benefits to those estimated above 15 . As such, the fuel consumption benefits of bottoming cycle systems were estimated to range from 6 to 10 percent. The range in fuel consumption benefits reflects variations due to sy stem sizing and whether the output is electrical (higher efficiency, more expensive) or mechan ical (lower efficiency, less expensive). The optimal working fluid is still an open question; both steam and organic Rankine bottoming cycles have been considered.
Manufacturers could not provide firm costing information on these sy stems, as they are still in the developmental stage. However, it was suggested that they expect to be able to offer payback in 18 to 24 months if development proceeds project ed. For a line-haul truck, this would suggest a low-end system cost of $7,200 to $8,400 for a system that gives 6 percent efficiency 16 . These capital costs are highly uncertain, and actual syst em costs may be much higher. We bracket the high-end cost of a bottoming cy cle at $15,100; this is based on the NESCCAF/ICCT estimate, which corresponds to a large system (32 kW) an d generates electric power, which adds to the balance of plant.

4.1.4 Diesel Engine Technology Packages
We estimated for the two diesel engine sizes how the various engine technologies would be implemented over the next 10 years. Table 4-12 s hows our projections for the large bore engines (11 to 15 L), and Table 4-13 shows our projecti ons for the small bore diesel engines. Our projections are mostly based on information obtained during site visits. Both these tables show

15 DOE 2008, pp 208-211

16 120,000 miles per year, $4.00 gallon fuel, 6 MPG4-21Table 4-12. Technology Road Map for 11-15 L Diesel EnginesEngineTechnology2007 Baseline2010 Engine2013 Engine2015 Engine2015 to 2020 EngineCylinderPressure190-210 Bar Increasing Cylinder pressureFuel system1,800 to 2,200 BarCommon rail or 33Kpsi Unit InjectorCommon rail, multiple injections per cycle, Higher injection pressureEmissionsControlMed-rate cooledEGR, DPF w/activeregenSCR, low-ratecooled EGR, DPFw/passive regenImproved cat conversion efficiency, advanced EGRAspirationVG Turbocharger Improved VG Turbocharger E-TurboEngine ControlsOpen-loop Closed-loop Improved Closed-loopWaste-heatrecoveryNoneMech. Turbo-compoundMech or Electric turbo-compoundBottoming cycleAccessoriesBelt-driven mech.Var disp pumps -or-electric accessoriesElectric accessoriesWeight2,200 to 3,100 lbs +400 lbs +450 lbs Similar to 2013 +750 lbsPeak Efficiency41 to 42 % 43.2 to 44.2% 45.5 to 47.5% 47.9 to 51.4% 50.6 to 53.5%Package Cost— $10K $14K $16.5K $23.5K4-22Table 4-13. Engine Technology road map for 6-9L diesel enginesEngineTechnology2007 Baseline2010 Engine2013 Engine2015 Engine2015 to 2020 EngineCylinderPressure170-280 Bar Increasing Cylinder pressureFuel system1,600 to 1,800 BarCommon rail or UnitInjectorCommon rail, multiple injections per cycle, Higher injection pressureEmissionsControlMed-rate cooled EGR,DPF w/active regenSCR, low-ratecooled EGR, DPFw/passive regenImproved cat conversion efficiency, advanced EGRAspirationVG TurbochargerImproved VG Dual StageTurbochargerE-Turbo, Dual StageEngine ControlsOpen-loop Closed-loop Improved Closed-loopAccessoriesBelt-driven mech.Var disp pumps -or-electric accessoriesElectric accessoriesWeight1,100 to 1,700 lbs +300 lbs Similar to 2010 Similar to 2013 Similar to 2015Peak Efficiency40 to 41 % 42 to 43% 43 to 45% 45 to 48% 46 to 49%Package Cost— $8.1K $10.3K $12.2K $13K4-23 the category of engine improvement (e.g. fuel sy stem), the 2007 baseline, and our estimates of technologies for 2010, 2013, 2015, 2015 to 2020.
From these technology roadmaps, engine p ackages were estimated for 2010, 2013-2015, and 2020 11 to 15 L engines with waste heat recove ry, 11 to 15 L engines without waste heat recovery, and for 6 to 9 L engines. Table 4- 14 shows the estimated capital costs for each package as well as a breakdown of the cap ital costs for each package component.
These results were then use to estimate the engine efficiencies, percent improvement (relative to 2007 baseline), capital costs, and weight for tractor trailer, motor coach, refuse hauler, and Class 3-6 applications and transit buses. Thes e results are summarized in Table 4-15.
The following sections provide deta ils as to the technologies and a ssumptions that were used to specify these engine technology packages.

Table 4-14. Engine technology package capital cost

Package Capital cost Components (Thousands of Dollars) 17

Pkg Total Capital costEmissionsFuel SystemCombustionControlsTurboAdv EGRVVAFrictionParasiticsWaste Heat

11 to 15L Engines, with Waste Heat Recovery 2010 $9.6 to $10.6K 9.5 0.125 0.375 — — — — 0. 125 — — 2013 $13.2 to $15.2K 9.5 0.25 0.75 0.1 0.1 0.75 — 0.25 — 2.5 2015 $14.7 to $18.2K 9.5 0.375 1. 125 0.1 0.5 0.75 — 0.375 0.75 3 2020 $21.4 to $25.9K 9.5 0.5 1.5 0.1 0.5 0.75 — 0.5 0.75 9.5 11 to 15L Engines, without Waste Heat Recovery 2010 $9.6 to $10.6K 9.5 0.125 0.375 — — — — 0. 125 — — 2013 $11.8 to $12.8K 9.5 0.25 0.75 0.1 0.1 0.75 — 0.25 — — 2015 $13.2 to $14.7K 9.5 0.375 1. 125 0.1 0.5 0.75 — 0.375 0.75 — 2020 $13.9 to $15.4K 9.5 0.5 1.5 0.1 0.5 0.75 — 0.5 0.75 — 6 to 9L Engines 2010 $7.6 to $8.6K 7.5 0.125 0.375 — — — — 0. 125 — — 2013 $9.8 to $10.8K 7.5 0.25 0.75 0.1 0.7 0.75 — 0.25 — — 2015 $11.5 to $13K 7.5 0.375 1. 125 0.1 1 0.75 0.3 0.375 0.75 — 2020 $12.2 to $13.7K 7.5 0.5 1.5 0.1 1 0.75 0.3 0.5 0.75 —

17 For technologies that include a cost range, the mid-point of the assumed cost is shown in the component breakdown.4-24 Table 4-15. Overview of engine technology packages
% FC Imp relative to... Pkg Engine Peak Thermal Eff. ’07 Baseline Prev. pkg Capital cost Wt

Tractor Trailer
2007 41 to 42% — — — — 2010 43 to 44% 4 to 5% — $9.6 to $10.6K +400 2013 45 to 48% 8.8 to 11.7% 5 to 7% $13.2 to $15.2K +450 2015 48 to 52% 13.4 to 18.3% 5 to 7.5% $14.7 to $18.2K +450 2020 51 to 53% 18 to 21.5% 2 to 4% $21.4 to $25.9K +700
Motor Coach
2007 41 to 42% — — — — 2010 43 to 44% 4 to 5% — $9.6 to $10.6K +400 2013 45 to 48% 8.8 to 11.7% 5 to 7% $13.2 to $15.2K +450 2015 48 to 51% 13.4 to 18.3% 5 to 7.5% $14.7 to $18.2K +450 2020 51 to 53% 18 to 21.5% 2 to 4% $21.4 to $25.9K +700

Refuse Hauler
2007 41 to 42% — — — — 2010 43 to 44% 4 to 5% — $9.6 to $10.6K +400 2013 45 to 47% 7.8 to 9.8% 4 to 5% $11.2 to $12.2K +400 2015 47 to 49% 12 to 14.7% 4.5 to 5.5% $12.7 to $14.2K +400 2020 48 to 50% 12.9 to 16.4% 1 to 2% $13.4 to $14.9K +400

Class 3-6 Box and Bucket and Transit Bus
2007 40 to 41% — — — — 2010 42 to 43% 4 to 5% — $7.6 to $8.6K +300 2013 43 to 45% 7.8 to 9.8% 4 to 5% $9.8 to $10.8K +300 2015 45 to 48% 12 to 14.7% 4.5 to 5.5% $11.5 to $13K +300 2020 46 to 49% 12.9 to 16.4% 1 to 2% $12.2 to $13.7K +300

4.1.4.1 2010 Engine
Although they are not yet sold, de tailed specifications of 2010 e ngines are currently available through company literature. Our 2010 engine pack age represents a loose consensus among the engine manufacturers of the technol ogies that they are offering in 2010-compliant engines. It is not meant to represent any single manufacturer’s technology strategy. This generic 2010 package omits two particular technology strategies th at are being used on some 2010 engines:4-25 • High-rate EGR emissions control system : Navistar is using an EGR only-based NO x strategy in their MaxxForce engines. Our 2010 engine package assumes that an SCR emissions control system is used. This re flects the fact thatthe other engine manufacturers are pursuing this approach.

• Mechanical turbo-compounding : Detroit Diesel has included a mechanical turbocompounding system in their 2008 DD15 and DD16 engines. They are the only US manufacturer to do so. The inclusion of the tu rbo-compounding system is likely driven in part by Daimler/Detroit Diesel’s strong presence in Europe, in which high fuel prices are more likely to lead to adopting such a t echnology. We consider turbo-compounding to become a technology strategy that will be more prevalent in the 2013 to 2015 time frame.
The technologies included in the 2010 engi ne package are summari zed in Table 4-16.

Table 4-16. 2010 engine technologies Engine Technology 11 to 15L 6 to 9L Cylinder Pressure 210 to 220 bar 190 to 200 bar Fuel injection Common rail 2,200 to 2,400 Bar fuel injection, Rate shaping, multiple injections per cycle Common rail 2,000 Bar fuel injection, Multiple injections per cycle

NO x Control SCR, low-rate cooled EGR SCR, low-rate cooled EGR Particulate Control DPF w/pass ive regen DPF w/passive regen Aspiration Elec. Actuated VG Turbochar ger Elec. Actuated VG Turbocharger Engine Emission Controls Open-loop Open-loop Waste-heat recovery None None
Accessories Belt-driven mechanical Belt-driven mechanical Weight +400 lbs (SCR system and DEF ) +300 lbs(SCR system and DEF) Peak Thermal Efficiency 43 to 44% 42 to 43% Package Cost $9.6 to $10.6K $7.6 to $8.6K

As a package, both the 2010 big-bore and medium- bore engines are estimated to offer a 4 to 5 percent reduction in fuel consumption compared to 2007 engines. This is based on published estimates from several manufacturers 18 and from feedback offered during site visits. Nominally, this fuel consumption benefit includes:

• SCR after-treatment allows for lower EG R flow, higher temperature combustion, and allows for passive regeneration of the DPF

—3 percent

18 Manufacturer brochures: Cummins ISX 2010 [Cummins 2009]; De troit Diesel DD15 [Detroit Diesel 2009], and Volvo SCR information [Volvo 2009]4-26 • Fuel injection system improvements

—1 percent

• Miscellaneous (friction, improved turbocharging)

—1 percent
In reality, this type of breakdown masks some of the differences among technology strategies that have been pursued by different companies.
The major additional capital cost for the 2010 engine is the SCR system. We have also assumed additional costs of $500 for more advanced fuel injection systems and design changes needed to enable higher cylinder pressures and $125 for fric tion improvement. In sum, the 2010 package is estimated to cost $9,600 to $10,600 for big bore engines, and $7,600 to $8,600 for medium bore engines.

4.1.4.2 2013 Engine
The 2013 engine package includes several enhancements to the 2010 engine. With static emissions requirements for the first time in a d ecade, manufacturers will be able to focus on improving the fuel efficiency of their engine offe rings. Some of the design changes that could be expected in this timeframe are:

• Closed-loop engine controls will be enab led by the onboard diagnostic systems mandated by the EPA. This change, coupled with continuing improvement of NO x -reduction catalysts will enable engines to be operated at higher thermal efficiency across their operating map. (1 to 2 percent fuel consumption benefit)

• Turbocharger efficiency improvements plus advanced EGR approaches to improve air handling. Medium-duty vehicles and refuse haulers might use dual-stage or series turbochargers due to their favorable respons e characteristics. (1 to 2 percent fuel consumption benefit)

• Incremental Friction improvements (0.5 percent fuel consumption benefit)

• Mechanical turbo-compounding, including VVA (only in heavy-duty, on highway vehicles) (2 to 2.5 percent fuel consumption benefit)
In combination, these technologies would increase brake thermal efficiency in 11 to 15L engines by 5 to 7 percent compared to the 2010 engine package or 9 to 12 percent compared to the 2007 baseline. Turbo-compounding is no t included for refuse vehicles, which lowers the efficiency improvement to 4 to 5 percent. The medium-bor e engines would not include mechanical turbocompounding but could benefit more from closed loop controls given that these engines operate over a wider portion of their map. These engines are projected to improve by 4 to 5 percent compared to the 2010 medium bore package or 8 to 10 percent compared to the 2007 baseline. Table 4-17 summarizes 2013 engine technologies.
Additional capital costs for the 2013 system (beyond those projected for 2010) include continuing enhancement to the fuel system and combustion chamber (~$500 total), friction reduction, advanced cooled EGR (~$750), and adva nced controls, sensors, and actuators for closed-loop controls (~$100) for both th e big-bore and medium-bore offerings.4-27 Table 4-17. 2013 engine technologies

11 to 15L 6 to 9L Cylinder Pressure 220 to 230 bar 210 to 220 bar Fuel injection 2600 bar, piezo-electric system 2400 bar

Emissions system 2010, w/improved catalyst conversion efficiency 2010, w/improved catalyst conversion efficiency and advanced EGR or VVA

Aspiration Improved VG Turborcharger, advanced EGR Dual-stage VG Turborcharger
Engine Controls Closed-loop Closed-loop

Waste-heat recovery Gen 1 Mech. Turbo-compounding (Optional) Cooled EGR

Accessories Belt-driven mechanical Belt-driven mechanical Weight +50 lbs (Turbo-compounding) Same as ‘10
Peak Thermal Efficiency 45 to 48% (w/WHR) 45 to 47% (w/out WHR) 43 to 45%

Package Cost $13.2 to $15.2K (w/WHR) $11.8 to $12.8K (w/out WHR) $9.8 to $10.8K

The big-bore engines, with the exception of the refuse hauler, also include mechanical turbocompounding ($2,000 to $3,000) and an improved turbocharger ($100). The medium-bore engines and the refuse hauler both include a dual-stage turbocharger ($700, incremental to a single-stage).

4.1.4.3 2015 Engines
The technology packages that might be marketab le in the 2015 timeframe are far less certain than the 2010 packages (which are soon to begin initial roll-out), and the 2013 engines, which are already being developed as part of the standard product development cycle.
During this timeframe, it is possibl e, perhaps likely, that hybrid-el ectric vehicles will come into the medium-duty segment, and perhaps in line-haul applications, in larg e numbers. If hybrids do capture a large portion of market, this would lik ely lead to a technology strategy that includes electric accessories, e-turbo, and electric wa ste heat recovery (ele ctric turbo-compounding, thermoelectric devices, or electric bottoming cycle) – all of which can interact synergistically with a hybrid vehicle. In this scenario, even non- hybrid vehicles could transition to some of these technologies if high produc tion volumes from hybrid s bring the costs down.

In the absence of electrificati on, manufacturers would focus inst ead on reducing parasitic loads using technologies such as variable displacement pumps a nd would continue to pursue mechanical waste heat recovery opportunities, such as mechanical turbo-compounding (perhaps enhanced from the 2013 incarnation) and mechanical bottoming cycle systems.4-28 In parallel, engine manufacturers are likely to roll out new engine designs during this timeframe. These could include next-generation fuel systems that could push fuel in jection pressures past 3,000 bar using piezo-electric or super critical fuel injecti on and new combustion chamber designs capable of still higher efficiency co mbustion, as well as reduced friction. VVA could come into the medium-duty segment during this timeframe. Table 4-18 summarizes the 2015 engine technologies.

Table 4-18. 2015 engine technologies Engine Technology 11 to 15L 6 to 9L Cylinder pressure 230 to 240 bar 220 to 230 bar Fuel injection 3,000 bar super critical system 2600 bar, piezo-electric system Emissions system Same as 2013 Same as 2013 Aspiration Electrically boosted VG Turbocharger Electrically boosted Dualstage VG Turbocharger plus VVA Engine Controls Improved Clos ed-loop Improved Closed-loop Waste-heat recovery Mech. turbo-compounding, Electric turbo-compounding, or None None

Accessories Variable displacement pumps -orelectric accessories Variable displacement pumps -or- electric accessories Weight Similar to 2013 Similar to 2013 Peak Thermal Efficiency 48 to 51% (w/WHR) 47 to 50% (w/out WHR) 45 to 48%

Package Cost $14.7 to $18.2K (w/WHR) $12.7 to $14.2K (w/out WHR) $11.5 to $13.0K

In combination, the 2015 big-bore package is pr ojected to reduce fuel consumption by 5 to 7.5 percent compared to the 2013 en gine, or 13.5 to 18 percent total. For the smaller 6 to 9L engines, the fuel consumption re duction is estimated to range from 4.5 to 5.5 percent compared to the 2013 engine package or 12 to 15 percent compared to the 2007 baseline. The range in percent improvement reflects the differences between mechanical and electric technology strategies. These improvements include:

• Improved fuel injection, combustion chamber de sign – 2 percent fuel consumption benefit

• Controls, e-turbo – 1 percent fuel consumption benefit

• Friction – 0.5 percent fuel consumption benefit

• Accessories – 1 percent (variable displacement pu mps) to 2 percent (electric accessories) fuel consumption benefit4-29 • Waste-heat – 0.5 percent to 2 percent fuel c onsumption benefit (11 to 15L Tractor trailer only)
Additional capital costs for this system include parasitic load reducti on strategies ($500 to $1,000), friction reduction ($125), el ectric turbocharging, and evol utionary engine improvements ($500). The marginal cost of addi ng an electric turbo-compound syst em to a big bore engine that is hybridized and includes a mechanical turbo-compound is estimated at $1,000.

4.1.4.4 2016 to 2020 Engine + Bottoming Cycle
Beyond 2015, engine improvements are highly uncerta in. The major addition to the 2020 engine package is a bottoming cycle, although we speculate that engines will con tinue to benefit from conventional incremental improvement opportunities, such as higher cylin der pressure, improved fuel systems, and better controls. During this ti meframe, we also speculate that electrification technologies will have come into the market and fully realize savings from high volume.

Table 4-19. 2016 to 2020 engine technologies Engine Technologies 11 to 15L 6 to 9L Cylinder pressure 240 bar 220 to 230 Bar Fuel injection 4,000 bar super critical atomization 3,000 bar

Emissions system Same as 2015 Same as 2015 Aspiration Electrically boosted VG Turbocharger Electrically boosted Dualstage VG Turbocharger Engine Controls Improved Clos ed-loop Improved Closed-loop Waste-heat recovery Bottoming cycle (optional) None
Accessories Electric accessories Electric accessories Weight +200 to 300 lbs (bottoming cycle) Same as 2015

Peak Thermal Efficiency 51 to 53% (w/WHR) 47 to 50% (w/out WHR) 46 to 49%

Package Cost $21.4 to $25.9K (w/WHR) $13.9 to $15.4K (w/out WHR) $12.2 to $13.7K

The big bore engine with waste heat recovery (WHR) offers an incremental savings of 2 to 4 percent compared to the high- end 2015 engine, giving a total fu el consumption reduction of 18 to 22 percent compared to the 2007 baseline. This is based on the assumption that the electric turbo-compound system (~4 to 5 percent efficien cy improvement) in the 2015 engine is replaced with a bottoming cycle that offers 6 to 8 percent efficiency improvement.
Depending on if the 2015 engine is assumed to include a mechanical or electric turbocompounding system, the incremental cost of the bottoming cycle is $4,000 to $9,000. We have4-30 assumed that bottoming cycle costs range fr om $8,000 to $11,000, which lies towards the low end of the range specified.
The medium bore engine does not include signif icant changes compared to the 2015 engine. We have included continued development of fuel systems, combustion, and friction reduction, which are estimated to offer fuel consumption re ductions on the order of 1 to 2 percent.
4.1.5 Gasoline Engine Technologies
Information on gasoline engine technologies was gathered primarily from the NHTSA light-duty study [2009], with additional supplemental in formation provided by the EPA [2008b] and by manufacturer websites. We receive d very little specific information regarding class 2b vehicles during our site visits.
This section will first define the baseline engine , then briefly discuss individual technologies that can be integrated into 5 to 8L gasoline engines, and finally combine these technologies into engine packages. Because both gasoline and diesel engines are present in this market segment, we have treated a transition to diesel engine technology as one potential “gasoline” engine package.
4.1.5.1 Baseline Gasoline Engine
Currently, both V8 and V10 gasoline engines, rangi ng in size from 5.4L to 8.1L, are sold for use in medium- and heavy-duty applications. We have assumed that the baseline gasoline engine is a port fuel injected, naturally aspira ted, fixed valve engine with 8 to 10 cylinders. This is based on survey of Class 2b gasoline engines that are currently sold. 19

4.1.5.2 Fuel Efficiency Strategies for Gasoline Engines
The NHTSA light-duty vehicle rulemaking uses a decision tree to packag e engine technologies together. This approach involve s incrementally adding technologi es in a way that reflects an anticipated manufacturer techno logy roadmap. Given that their analysis extends up to V8 engines for use in trucks that weigh up to 8,500 lbs, we felt it reasonable to extend their analysis to the V8 and V10 engines that are currently used in the Class 2b vehicles. As appropriate, we have scaled the NHTSA cost estimates for engi ne size using similar methodology to that applied in their rulemaking.

One of the intricacies of the decision-tree a pproach employed by NHTSA is that changes in engine configuration can dictat e a different technology path. Fo r example, according to their analysis, engines that use an overhead valve (OHV) configuration would a dopt technologies in a different order than those with a single (S OHC) or dual (DOHC) overh ead cam. A review of currently available large gasoline engines s howed that they primarily use an SOHC configuration. As such, we have followed the technology pathway that is defined for SOHC and DOHC engines. A summary of these NHTSA-derived estimates is shown in Table 4-20. In this

19 This is based on survey of Class 2b gas oline engines that are currently sold [Ford 2009a, Ford 2009b, GMC 2009, Dodge 2009]4-31 Table 4-20. Gasoline engine technology capital costs and benefits
Incremental Capital Cost and Benefit Technology Incremental to... % FC Benefit Cost

Friction reduction — 0.5 to 2.5% $110 to $500 a Variable Valve Timing (VVT) Friction 1 to 3% $122 Variable Valve Lift (VVL) b VVT 1 to 3.5% $400 to $750 Cylinder Deactivation c VVL 2.5 to 3% $75

Stoichiometric GDI d Cyl. Deactivation 2 to 3% $512 to $930
Turbo charging and Downsizing S-GDI 2.1 to 2.2% $1,229
Diesel — 19 to 24% $7,900 to $9,400 Lean-burn GDI S-GDI 10 to 14% $750 Gasoline HCCI S-GDI 10 to 12% $685

Accessory Electrification Applicable to any package 2 to 4% $1,000 to $2,000 (current) $500 (high volume)

a $13 to $49 per cylinder + $5 for lubricants

b $51 per cylinder for discrete VVL; $70 to $75 per cylinder for continuous VVL

c Offers marginal benefit on DOHC engines; these benefits reflect SOHC

d $64 to $93 per cylinder

table, the capital cost s and benefits of each technology ar e expressed in terms of their incremental benefit to the technology specified in the second column.
The following is a description of each of the technologies included in the table:

Friction reduction : Includes advanced lubricants, low tens ion piston rings, roller cam followers, improved crankshaft design and bearings, material coatings, material substitution, and piston and cylinder surface treatments.
Variable Valve Timing (VVT): Reduces gas exchange loss by alte ring the timing of the intake and exhaust valves. Several implementations we re considered, including intake cam phasing, coupled cam phasing, and dual cam phasing.

Variable Valve Lift (VVL) : Reduces gas exchange loss by alte ring the cam profile; this reduces the amount of throttling required. Th is can be implemented as a series of discrete cam profiles, or, for slightly improved efficiency, a continuously varying profile.
Cylinder Deactivation: Reduces gas exchange loss by deactiv ating half of the cylinders when the engine is operating at low load.4-32 Stoichiometric Gasoline Direct Injection (S-GDI): Injects gasoline directly into the cylinder, which cools the air-fuel mixtur e as gasoline evaporates. This allows for higher compression ratio, which in turn, redu ces exhaust gas losses.
Turbocharging and Downsizing: Boosting an engine (increasing the intake pressure using a turbocharger) can be used to increase the power density of an engine. This enables engine downsizing – which reduces engine friction. Turbocharging also reduces gas exchange losses by increasing engine load and reducing throttling.

Diesel: Shifting from gasoline to diesel engines offers significant fuel efficiency benefits. This is primarily due to higher compression ratios and re duced gas exchange losses. However, it should be noted that, due to emissions re gulations (which have degraded the efficiency of diesels) and advances in spark-ignition t echnology (e.g., HCCI, turbocharging), the difference between gasoline and diesel thermal efficiency has narrowed considerably. NHTSA estimates the incremental cost of a diesel engine with 2010 emissions treatment at $7,000; this estimate may be too low. A review of current (2007-comp liant) diesel engine up charges on Dodge [2009], GMC [2009], and Ford [2009a] trucks shows th at incremental costs range from $6,100 to $8,600. Feedback offered on site visits suggested that the 2010 emissions package for these vehicles will add an additional $1,800. Adding this estimate to th e range of current engine prices, we have assumed an incremental cost for diesel of $7,900 to $9,400. The NHTSA rulemaking does not assume a fuel consumption benefit for using an SCR system; we have used their estimate but note that it may underestimate the efficiency ga in in going from a gasoline to diesel engine.
Lean-Burn Gasoline Direct Injection (LB-GDI): Uses a lean, carefully controlled fuel injection to improve efficiency beyond that offered by stoichiometric GDI by reducing gas exchange losses. This technology re quires the addition of a lean NO x trap and ultra-low sulfur gasoline. Because it requires low-sulfur gasoli ne, NHTSA did not include it in their rulemaking. We have included it here as a separate package; its capital costs and benefits use estimates from EPA and are expressed relati ve to stoichiometric GDI.

Gasoline HCCI: Gasoline homogeneous charge compression ignition (HCCI) uses pre-mixing of fuel and tightly controlled combustion condi tions to achieve higher compression ratios than can be achieved by conventional gasoline engines. Th is allows the gasoline engine to approach diesel-like efficiencies. These systems are still in development and hence are unlikely to come to market in the near-term. NHTSA did not include th em for this reason; we have included them as a possible market entrant in 2014. The cost of ga soline HCCI is estimated from EPA [2008b] at $685, incremental to the cost of stoichiometric GDI.
Accessory Electrification: The NHTSA rulemaking does not include improved accessories as an option for large trucks. This is because they are not currently offered at high volume and will likely require higher voltage (42V) systems. We have included accessory el ectrification here on the logic that our analysis has a longer time horizon than does the NHTSA rulemaking. For the vehicle classes to which electric accessories do apply, NHTSA estimates an incremental cost of $275 to $330 for technologies such as electric power steering, an improved a lternator, electric air conditioning, and electric coolant pumps. We have extended these estimates to include additional hardware to go to a 42V system (estimated at $200). This give a high-volume cost of $475 to $530. At current low volumes, costs are much higher – we have estimated $1,000 to $2,000,4-33 based on feedback received during site visits. El ectric accessories are estimated to offer a 2 to 4 percent fuel consumption benefit.
4.1.6 Class 2b Engine Packages
We have largely followed NHTSA’s lead in pack aging gasoline engine technologies for Class 2b vehicles but have included additi onal packages for HCCI and lean- burn GDI, with the caveat that these are still in the developmen t stage and, in the case of lean-burn GDI, require low-sulfur fuel. The capital costs, benefits, and description of technologies for each of the Class 2b engine packages are included in Table 4-21. We have not included electric acce ssories in any of the engine packages; rather, they may be considered as an add-on to any of the future packages. To clarify, our approach for these engine packages differs from that used in packaging diesel engines in several ways:

 Both diesel and gasoline engi nes are considered. It should be noted that, if the diesel pathway is followed, then the technology road map described for small (6 to 9L) diesels may be followed. The logic behind this approach is that both gasoline and diesel engines compete in this market segment.

 Most of the technologies identified are av ailable and being depl oyed in some vehicle segments now. As such, packages are defined in terms of how far down the NHTSA decision tree they rest, as di stinguished from their year of introduction. For example, the “Turbo GDI” package builds on the GDI packag e (by turbocharging and downsizing the engine).
Table 4-21. Class 2b engine technology packages

Package Capital Cost FC Benefit Intro YearFrictionVVLVVTCyl. DeactivationS-GDITurboGasoline HCCILB-GDIDiesel

VVL and Turbo $632 to $1,372 2.5 to 9% 2010 X X X GDI $1,200 to $2,400 7 to 14% 2012 X X X X X Turbo GDI $2,500 to $3,600 11 to 17% 2012 X X X X X X ’10 Diesel $7,900 to $9,400 19 to 24% 2010 X X L.B. GDI $3,250 to $4,350 20 to 29% 2014 X X X X X X X Gas HCCI $3,185 to $4,285 20 to 27% 2014 X X X X X X X Elec. Acc. $500 to $2,000 2 to 4% 20144-34 4.2 Aerodynamics

4.2.1 Overview
The power (P) required to overcome aerodynamic drag on a vehicle is a function of the vehicle’s frontal area (A), the vehicle velocity (V), air density ( ρ ), and the vehicle’s shape (expressed in terms of the coefficient of drag, or C D ):

P = 0.5 ρ V 3 A C D Equation 3
Of these factors, vehicle velocity has the grea test influence at high ve hicle speeds. This is because aerodynamic drag increases with the cu be of speed. The relative impact of reducing aerodynamic drag is illustrated in Figure 4-5 fo r an 80,000 lb vehicle with a frontal area of 116 ft 2 . As shown in this figure reducing aerodynamic drag by a third from 0.6 to 0.4 has a large effect at higher speeds. The power to overcom e drag dominates the power to overcome rolling resistance after about 50 to 65 MPH.

Figure 4-5. Influence of aerodynamic drag on vehicle power demand as a function of speed

A widely cited rule of thumb in industry is th at, for a vehicle traveling 60 MPH, a 2 percent reduction in aerodynamic drag reduces fuel consum ption by 1 percent. The practical outcome of this observation is that reducing aerodynamic drag offers the great est benefit on duty cycles that travel at highway speeds for a good portion of th eir trips. Table 4-22 shows the approximate benefit, based on assumed highway speeds, of reducing aerodynamic drag for the various truck4-35 classifications that form the focus of this study. As shown, the tractor trailer and the motor coach both gain the most benefit from improving th e vehicle’s aerodynamic drag. In addition, both straight box trucks and Class 2b pickups and vans could benefit from these types of improvements – particularly for trucks within th ese classes that spend significant time on the highway. The bucket truck, refuse vehicle, and urban transit bus – which spend the majority of their time traveling at low speeds – gain minimal benefit from drag reduction.

Table 4-22. Impact of Highway Speed on Aerodynamic Improvement Potential

Truck Application Highway Average Speed (MPH) Approximate % FC Benefit for 1 Percent

Reduction in C D 20 Efficacy of Aerodynamic Improvements Tractor trailer 55 to 65 ~0.5% High Motor Coach 50 to 60 ~0.4% High Straight Box Truck 25 to 35 ~0.25% Medium 2b Pickups and Van 25 to 35 ~0.25% Medium
Bucket Truck 15 to 20 ~ 0.1% Low
Refuse 10 to 15 < 0.1% Low
Urban Transit 10 to 15 < 0.1% Low

It should also be noted that in addi tion to lowering the drag coefficient (C D ), aerodynamic force could also be reduced by either reducing the average speed of the ve hicle (lowering the V 3 term in Equation 2), or reducing the vehicle’s frontal area (lowering the A term in Equation 2). The efficacy of limiting road speed is discussed in Section 4.8. Reducing vehicle frontal area is a challenging prospect for most of the vehicle cl asses under consideration given their operational characteristics. For example, reducing the height of the trailer in a co mbination vehicle would reduce the total frontal area of th e vehicle but at the expense of either ground clearance or cargo capacity. The exception to this is the Class 2b pi ckups and vans, which have less rigidly defined operational parameters.
Estimates of the fuel savings pot ential of aerodynamic devices are based on a literature review of and discussions with sources that include tr uck manufacturers, trailer aerodynamic device manufacturers, and labs that have conducted wind tunnel test or co mputational modeling of different fuel savings technologi es. The results reported by these sources tend to be reported either as percent changes to the coefficient of drag (C D ) or fuel consumption benefit, typically at a constant speed of 55 to 65 MPH. For cases in which benefits are reported in terms of a coefficient of drag, the fuel consumption benefi t is assumed to be one half that of the C D at 65 MPH (i.e., 2 percent change in C D gives 1 percent change in FC) and one quarter that of the C D at 30 MPH (i.e., 4 percent change in C D gives percent change in FC).

20 Note that the data shown in this column reflects estima tes based purely on average vehicle speed – it does not take into acco unt the non-linear impacts of deviations from this average speed. Actual simulation ov er a well-defined drive cycle would be needed to estimate the actual elasticity of C D on fuel consumption4-36 Data from this literature review may be base d on the results of computational fluid dynamics (CFD) modeling, wind tunnel tests s imulating travel at constant speed (typically 65 MPH) for both full-sized or scale-model vehi cles, controlled tests on a track (t ypically at a constant speed of 65 MPH) 21 , or actual in-use results from fleet test ing. None of these measurement techniques is perfect. For example, wind tunnel tests o ffer robust measurements of the change in C D under controlled conditions but do not offe r actual estimates of fuel cons umption benefit in real-world operation. A summary of these strengths and weakne ss is provided in Table 4-23. To the extent possible, the data reflects the fuel consumption benefits or drag benefits of wind-averaged data (i.e., collected over a sweep of wind headings). Wind-averaged measurements are standard practice in wind tunnel tests; si milarly, real-world fleet test s should reflect wind-averaged results. It is less clear that th is is the case for results conducted on track tests at constant speed.

Table 4-23. Comparison of aerodynamic evaluation methodologies
Strengths Weaknesses Computational Fluid Dynamics (CFD) Modeling • Simple, low cost

• Useful for initial screening and down-selecting designs • Does not accurately capture complexity of vehicle dynamics

Wind tunnel testing • Fully controlled environment

• Robustly estimates C D • May miss some nuances of actual in-use vehicle dynamics

• Does not directly measure fuel consumption

Test track • Actual data on fuel consumption

• Controlled conditions • Does not necessarily represent a realistic duty cycle

• High variance between individual test runs

• May not test wind-averaged drag

In-use fleet test • Realistic duty cycle

• Actual data on fuel consumption • Results may not be broadly applicable

The results presented in the tec hnology matrix presented in Secti on 3 represent a synthesis of the results from a number of sources. For devices fo r which there is wide variance in the reported benefits, we have attempted to explain possibl e reasons for the discrepancy and make reasoned judgments about which results seem most cr edible. We have attempted to group similar aerodynamic devices together. As such, a range in device costs and be nefits reflects both variations between implementing a given devi ce and variations due to duty cycle.

The next sections discuss our research on the capital cost and benefits for aerodynamic devices for heavy duty applications of Class 8 tractors and trailers, straight tr ucks, and motor coaches and for light duty applications of Class 2b pickup s and vans. No estimates were made for bucket trucks, refuse haulers, or transit buses. These applications spend a larg e fraction of their duty

21 These tests typically follow the SAE Type II test procedure. This is a well-defined procedure for measuring fuel use across multiple trials under controlled test conditions. However, the SAE Type II test does not define an actual drive cycle.4-37 cycle performing low speed stop-and-go driving and therefore will not benefit as much as other applications.

4.2.2 Class 8 Tractor Trailers
Strategies for reducing the aerodyna mic drag of combination tractor trailers can be broadly categorized according to whether they focus on the tractor, the trailer, or optimization of the tractor/trailer inte rface. Our estimates for the potential fuel consumption reduction for these different categories are summarized in Table 4-24. Of these categories, present-day trucks have already adopted many of the improvements that reduce drag on the tract or, and fleets have

Table 4-24. Class 8 tractor trailer aerodynamic technologies
Technology FC Benefit C D Improvement Capital Cost Status

Tractor Aero Roof Fairing 7 to 10% 15 to 20% $500 to $1,000 Standard Deflector, Day cab 4 to 7% 13% $1,000 to $1,300 Most Chassis Skirt 3 to 4% 4 to 7% $1,500 to $2,000 50 to 60% Side Extender 2 to 3% 4 to 5% $300 to $500 80 to 90% Next Generation Aero 3 to 4% 6 to 8% $2,750 2012 Intro

Trailer Aero Partial Skirt 2 to 3% 2 to 6% $1,500 to $2,000 Demos

Full Skirt 4 to 5% 5 to 11% $2,000 to $4,000 Demos Partial Gap 1 to 2% 2 to 4% $800 to $1,000 Demos Full Gap Fairing 2 to 3% 4 to 6% $1,000 to $1,450 Demos Boat Tail 4 to 6% 6.5 to 9% $1,500 to $2,000 Demos Aero Packages
No aero -10 to -12% -22 to -25% — — Smartway Tractor — — — Baseline Smartway Tractor +

Smartway Trailer 5 to 6% 10 to 12% $3,000 per trailer 2010 to 2012

Improved Smartway Tractor + Smartway Trailer 7 to 9% 15 to 17% $2,750 + $3,000 per trailer 2012 to 2013

Full Aero Tractor & Trailer 11 to 12% 22 to 24% 22 $2,750 + $4,000 per trailer 2013 to 2014

22 Assumes C D benefit of full trailer package is 17 to 19 percent4-38 adopted many strategies that aim to optimize th e tractor/trailer interf ace. However, trailer aerodynamic design improvements have not yet been adopted into the fleet in significant numbers. We assume that th e baseline vehicle has a C D of 0.58 to 0.6 based on data from a number of sources [Marinko 2009, Sa lari 2009, Storms 2004, Ang-Olson 2002]. 23 This is consistent with an aerodynamic tractor pul ling a standard 53’ box trailer without any aerodynamic improvements. The aerodynamic tractor includes an integrated roof fairing, cab side extenders, chassis fairings , and an aerodynamic chassis. Thes e features are described in greater detail below.
Given the prevalence of aerodynamic tractors al ready on the market, the best opportunities for further reducing aerodynamic drag of combinati on trucks stem from deployment of trailer aerodynamic devices and from improved design integr ation between the tract or and the trailer. Coupled with continued incremental improvements to the tractor, these improvements to vehicle aerodynamics have the potential to reduce drag by 25 to 30 percent and reduce fuel consumption by 10 to 15 percent.
There may be an additional oppor tunity to reduce vehicle drag by incentivizing independent owner operators and less-than-truc kload fleets to more fully adopt drag reduction devices that are already available and prevalent in the large commercial fleets.

4.2.2.1 Tractor Aero
Modern tractors have already introduced a number of design features that optimize body contours to streamline airflows. These include aerodynamic bumpers and mirrors, sloped hoods and windshields, and rounded corners. In additi on, OEMs offer several aerodynamic options for Class 8 tractors. These include “roof fairings” (also called “air fair ings” or “roof deflectors”), cab side extenders, and chassis fairings (also known as “chassis skirts”, “fuel tank skirts”, or “fuel tank fairings”). Examples of these different devi ces are shown in Figure 4- 6 for a typical sleeper tractor. Roof fairings match the he ight of the tractor to the height of the trailer and streamline the air flows coming off the top of the vehicle. Cab side extenders reduce the gap between the tractor and the trailer, thereby reducing airflow through the gap. Chassis fairings streamline flows along the side of the tractor. A partial chassis fairing extends the length of the cab (typically just covering the fuel tank), while a full fairing extends all the way to the first drive axle.

23 The NESCCAF/ICCT study assumes an average drag coefficient of 0.63. However, this is based on data from an older Kenworth T600 Truck, which is not a full Smartway cab; it is meant to reflect an average of the line-haul trucks that are currently on t he road. In separate conversations with Ka mbiz, Salari, and Fritz Marinko, it was s uggested that a slightly lower baseline C D would be appropriate.4-39 Figure 4-6. Standard sleeper tractor aero technologies [Kenworth 2008]

These devices are also available for day cabs although the options tend not to be as integrated in design and function.
In tandem with deployment of these aerodynamic de signs, it is standard pr actice to optimize the interface between the tractor and the trailer for the specific load that is being hauled. This entails adjusting the height and profile of the roof fairing to match the trailer, adjusting the position of the wheels, and adjusting the length of the cab side extender. For example, a tractor that typically pulls a box trailer would use a highe r roof fairing than one that t ypically transports equipment on a flatbed.
In combination, a fully aerodynamic tractor that is properly matched to its load has been shown to reduce aerodynamic drag by 17 to 25 percent comp ared to a baseline vehicle that does not implement any of the devices described above [Cummins 2007, Kenworth 2008, Leuschen 2006]. This fully aerodynamic tractor would redu ce fuel consumption by approximately 10 to 12 percent. Most of this benefit comes from the roof fairing, but other features offer significant additional benefit.
Additional opportunities fo r reducing drag on the tractor were identified during site visits and discussions with experts. These include minor modifications to airflows along the chassis (for example, reshaping the hood, windshield, and front bumper), reducing the aerodynamic profile of mirrors; improving airflows al ong the underbody, and adding skirts or fairings to the wheel wells. Successfully implementing these future ad justments could require changes to existing regulations and operationa l considerations related to mirror size and tractor width. They must also be balanced against other considerations su ch as providing adequate air flow for cooling the engine system, which is a frequently sited c oncern for design changes to the underbody or the front grill. One manufacturer suggested that the packaging flexibility offered by electrified accessories – which need not be coupled directly to the engine – might yield significant benefits as an enabler for improved aerodynamics.4-40 Another factor that can increase aerodynamic drag is truck selection and specification. While the most aerodynamic vehicles have adopted many, if not all, of the features described above, there continues to be some market pull for tractors th at have a more traditional flat-nose design and that do not include all of the fairings describe d above. This tendency is particularly prevalent among independent-owner operators, who are more sensitive to first cost and more likely to consider vehicle styling in their purchase. For example, according to company literature from Navistar, their ProStar tractor – wh ich is marketed to large fleets – has 7 percent lower drag than their LoneStar offering, which is marketed to independent owner/operato rs; during site visits, other manufacturers suggested similar differen tiation between their aer odynamic models and their flat-nosed, less aerodynamic options. Figure 4-7 compares the vehicle styling of the two.

Prostar LoneStar
Figure 4-7. Prostar and LoneStar Tractors [Navistar.com]

It should also be noted that several features th at are commonly purchased by truck buyers have a negative effect on aerodynamic dr ag. These include large mirrors (2 percent reduction in drag, compared to aerodynamic mirrors), fender mounted spot mirrors (1 to 2 percent per mirror), bug deflector (~2 percent), and splash guards (~0.6 percent) [Leuschen 2006, Site Visits].
Feedback during site visits with manufacturers suggested that thes e types of improvements to the tractor’s aerodynamics could yield an additional 3 to 4 percent fuel consumption benefit beyond4-41 that seen in today’s Smartway-certified tractors . The combined cost of these “next generation” improvements is estimated to be $2,750. This estimate is arrived at as follows:

• $750 for additional cab streamlining. This is based on estimates from Vyas [2002] which estimates the incremental cost of cab st reamlining for a previous generation of aerodynamic improvement.

• $500 for an underbody treatment. This is similar to the cost of a partia l chassis fairing or a standard cab side extension.

• $1,500 for wheel skirts. This is similar to the cost of a chassis fairing.
4.2.2.2 Trailer and Tractor/Trailer Interface Aerodynamics
Salari [2008] estimates that the trailer contribut es 34 percent of the to tal vehicle drag, and 66 percent is contributed by the tractor. However, as discu ssed above, the tractor aerodynamic profile has already been largel y optimized. Going forward, there are a number of opportunities available to reduce trailer drag and, by potentially optimizing the tractor and trailer as a single unit, to better integrate the design between the two. It is further estimated that of the 34 percent drag contribution on the trailer, 16 percent come s from the trailer body and 18 percent from the trailer axle and wheels (i .e., the underbody). In addition, a porti on of the drag off of the tractor may be reduced by optimizing th e tractor/trail er interface.
Current trailers do not typically include any aerodynamic features. A number of devices have been tested in limited fleet deployments and are co mmercially available as retrofit options from a number of small independent companies. None of the major trailer manufacturers or truck OEMs has currently integrated trailer aerodynamics into their product offerings, and users have not yet widely adopted them as retrofit options.
Options for reducing the aerodynamic drag of the tr ailer underbody include side skirts of varying lengths and configurations, belly boxes, or axle bogey fairings (Figure 4-8).
The drag profile of the trailer body may be re duced by aerodynamic boat tails (also called “base flaps”, “base treatment”, etc.), which include both structural and inflatab le devices that extend off the rear of the trailer (Figur e 4-9). Drag from the tractor/tra iler interface can be addressed by design modifications to either the tractor or the trailer; examples of trailer modifications are shown in Figure 4-10.
There is wide range of estimates in the lite rature as to the efficacy of trailer aerodynamic devices, particularly in comparison to the rela tively narrow range of estimates we found for tractor drag reduction. This is due to a number of factors: there are many di fferent configurations and no clear consensus as to the single best ap proach, and there have been limited numbers of real world fleet tests, meaning that data sour ces are drawn largely from track tests by device makers or wind tunnel laboratory tests. It is al so possible that the current approach of using retrofit devices that are installed post-manuf acture leads to sub-optimal implementation. An additional confounding factor is that the benefits of these devices are not necessarily additive.4-42 Figure 4-8. Examples of trailer side skirts [Laydon 2009, Freight Wing 2009]

Figure 4-9. Examples of trailer base treatments (boat tail on the left, structural base flaps on the right) [Aerovolution 2009, AT Dynamics 2009]

Figure 4-10. Examples of trailer gap treatments – front fairing (left), and splitter plate (right) [NoseCone 2009]

To help address these issues, we compiled a compre hensive list of estimated benefits for trailer and tractor/trailer interface aerodynamic options. Because there is so much variation in how devices can be configured, it was instructive to characterize devices into one of several categories:4-43 • Base flaps , which include both structural and inflatable boat tails

• Full skirts : Refers to a skirt that runs the length of the trailer and extends most of the way to the ground. It may include a combined skirt and belly box.

• Partial skirts : Refer to a skirt that covers only a portion of the trailer underbody and does not extend all the way to the gr ound; this also includes belly boxes.

• Partial gap fairings : Narrows the gap beyond current standard practice, which is typically around to 40”, to 20 to 30”.

• Full gap fairings : Fully closes the gap between the tractor and the trailer

• Partial Trailer Aero Package: Includes two out of the th ree basic aerodynamic drag reduction approaches (rear base, underbody, and gap), but it may not use the most aggressive implementation of these devices. For example, a partial skirt and boat tail would constitute a “partial package.”

• Full Trailer Aero Package: Includes all three of the ba sic aerodynamic drag reduction approaches (rear base, underbody, and gap). Fo r example, a full or partial skirt, base treatment, and a partial gap treatmen t would constitute a “full package”.
Figure 4-11 shows the range of fuel consumption benefits that were found based on this survey of the available litera ture. This data includes the results of CFD modeling, laboratory wind

1.3% 2.2% 3.5% 5.2%

4.3% 5.8% 9.3%

0% 2% 4% 6% 8% 10% 12% 14%

012345678 Fleet Tests Track Wind Tunnel or CFD Average

Partial Gap Not included in average

Full Gap Partial Skirts Full Skirts Base Flaps Partial Pkg Full Pkg

Figure 4-11. Survey of Trailer Aerodynamics (see Table 4-25 for detailed sourcing)Fuel Consumption Benefit

Aerodynamic Devices4-44 Table 4-25. Summary of Aerodynamic Retrofit Devices Literature Review4-45 tunnel tests, and on-road demonstr ations by device manufacturers, fleets, and OEMs. All of the data is sourced from publicly available litera ture. To facilitate comparison between different sources, drag reduction benefits were converted to a fuel co nsumption benefit by dividing C D by 2. The data shown in Figure 4-11 provides a high- level summary of the efficacy of trailer drag reduction options; individual appr oaches and results are discu ssed in further detail in the following sections.
We estimate that implementation of a partia l aerodynamic package gives fuel consumption benefits on the order of 5 to 7 percent, and a full aerodynamic package offers benefits on the order of 9 to 10 percent.
4.2.2.3 Design Integration of the Tractor/Trailer Interface
The gap between the tractor and th e trailer is a major source of aerodynamic dra g, particularly at non-zero wind yaw angles (i.e., in a cross-wind condition). For ex ample, wind tunnel tests have shown that a non-optimized gap (i.e., no roof fa iring, 60” gap) can increase aerodynamic drag on the order of 35 percent in cross-wind conditions . With no wind, this effect on drag drops to nearly zero [Storms 2004].
Continually narrowing this gap and streamlining ai rflows from the tractor to the trailer offer continuous benefits. It is suggested in the litera ture that reducing the ga p by 10” reduces drag by 0.5 to 1 percent, with benef its continuing all the way to a fully sealed gap [Storms 2004, Kenworth 2008, Cummins 2007]. Although maximally be neficial from the perspective of fuel efficiency, a sealed gap presents a major operation al challenge due to the restrictions on vehicle turning radius and maneuverability. Figure 4- 12 shows one concept for reducing the tractor trailer gap.

Figure 4-12. Example of a trim top roof fairing [Leuschen 2006]4-46 A number of options for addressi ng the trailer/trailer gap have b een considered experimentally, some of which are mounted on the trailer, and some of which are mount ed from the tractor:

Tractor:

• As discussed above, it is sta ndard practice to employ cab side extensions and move the tractor fifth wheel forward to the extent allowed by load and route characteristics 24

. Collectively, these might narrow the interface from 60” to about 40” [Marinko 2009, Salari 2009]. These adjustments, coupled with th e roof fairing, greatl y mitigate the drag contribution from the tractor/trailer interface to the total vehicle drag.

• Extended cab side extenders may be used to fu rther narrow the gap beyond that of standard extensions; this approach would also include a roof fairing exte nsion to match the length of the cab extensions. Such a system may deploy to fill part of the gap or the entire gap. One approach to addressing operational issues with a fully sealed gap deploys the extensions at speeds over 35 MPH. Wind tunnel tests by In ternational and Mack [TMA 2006] and by CNRC [Leuschen 2006] measured the benefit of gap sealing devices to range from 2 to 4% reduction in total drag.

• A “trim top” roof fairing extens ion fits horizontally along the t op of the roof fairing, closing the gap over the top. This device has demonstrat ed fuel efficiency improvements on the order of 1 percent [TMA 2006, Leuschen 2006].

Trailer:

• Trailer front fairing (“nose cone ”), attached to the front of the trailer, extending across the top and possibly down the sides of the trailer

• A gap splitter plate, also called a “vortex gene rator”, which extends to wards the tractor along the vertical axis of the trailer.
It is not clear that there is any distinct fuel efficiency advantage to optimizing the gap from the trailer front versus the cab rear. Rather, factors that discriminate between trailer front fairings vs. cab extensions include: (1) trailer front devices re quire one treatment per trailer, so may be more costly, and (2) it may be problematic to add extens ions to cabs that pull many different types of loads. As such, trailer front fairings are most attractive for users that pull varied loads, while extended tractor extensions may be most attractive for large fleets that pull relatively homogeneous loads.
Results from a variety of tests showed drag bene fits on the order of 2 to 4 percent for a partial treatment with up to a 6 percent drag reduction for a fully sealed gap. These results correspond to a 1 to 2 percent fuel consumption benefit for a pa rtial treatment, and a 2 to 3 percent benefit for a

24 The relative axle position is constr ained by bridge formula load limits, which vary depending on a vehicle’s load and which br idges it needs to cross.4-47 full treatment 25 . In practical terms, a fully sealed ga p presents major challenges given turning radius requirements. Some manufacturers have explored addressing this issue by using a gap treatment that fully deploys only at high speeds. However, this may add considerable cost and complexity for a relatively marginal additional benefit.
Costs on trailer front fairings are published for two different manufactur ers and range from $800 to $1,450 [FreightWing 2009, Nosecone 2009].

4.2.2.4 Trailer Underbody Treatments
The majority of trailer underbody treatments consis t of side skirts that extend the length of the trailer, thereby lessening the gap between the bottom of the trailer and the roadway. There are a number of different skirt configur ations that have been proposed or a currently available. These vary in terms of:

• Length : Some skirts extend only a few meters al ong the trailer underside in front of the wheels; others extend the full length of the tr ailer to the rear wheels and include a short section that extends to the rear of the wheels.

• Material : Both aluminum and composite skirts have been considered. Aluminum skirts are lower cost but weigh more.

• Height : The lower the ground clearance of a skirt, the greater the fuel consumption benefits. However, this must be balanced against the practical constraints im posed by obstacles that could damage the device.

• Durability : To address ground clearance issues, some manufacturers sell a flexible skirt; others offer skirts that retract at low speeds and deploy at high speed.
Other underbody treatments include “belly boxes”, which are simp le boxes that attach to the trailer underside, or trailer bogey fairing, which smoothes airflows around the rear axle. Benefits of a belly box are generally reporte d to be similar to those of a pa rtial skirt and are treated as a variation on a partial skirt in this analysis 26 . Bogey fairings have been demonstrated to offer fairly minor drag reduction benefits – on the or der of 2 percent. Several studies tested the benefits of using a belly box in combination with skirts and f ound that the combination reduced drag by an additional 3 percent [TMA 2006, Stor ms 2004]. To our knowledge, neither of these devices is available commercially – likely due to a combination of implementation issues and lower benefits.

Data from skirt manufacturers estimate the fuel c onsumption benefit of full skirts range from 4 to 7 percent [Laydon 2009, AT Dynamics 2009, Freight Wing 2009, Windyne 2009, AdamWorks 2009]. One skirt manufacturer also cites data on a pa rtial skirt, for which a 4 percent benefit is

25 One source cited much higher fuel consum ption benefits as high as 14 percent; however, it appears that this is relative to a baseline tractor that does not include any aerodynamic treatments. It is also not clear what test methodology was used [NoseCone].

26 Both International and Mack evaluated belly boxes as part of the TMA [2006] study, as did Storms [2004].4-48 claimed [Freight Wing 2009]. Independent tests show fuel consumption benefits that are considerably lower than these. There is a fair amount of variation in the data, but in the aggregate, full skirts are estimated to offer fuel consumption benefits of 4 to 5 percent, while partial skirts offer benefits of 2 to 3 percent. Measured drag reductions range from 5 to 11 percent for full skirts, and 2 to 6 percent for partial skirts [TMA 2006, Leuschen 2006, Leuschen 2005, Storms 2004, Salari 2008, Site Visits]. The be nefits reported by independent tests seem more credible than those reported by device manufact urers. This is the case both insofar as that they are more consistent with f eedback obtained on site visits, and they are more consistent with our subsequent review of trailer aerodynamic packages.

Price on skirts that are currently available varies from a pproximately $1,500 for relatively basic designs (i.e., rigid design, unret ractable) to up to $4,000 for a fully retractable design [Site Visits, Freight Wing 2009, Windyne 2009].

4.2.2.5 Boat Tails

Boat tails attach to the rear of the trailer, reducing aerodynamic drag due to the trailer’s wake. Two basic designs have been cons idered: rigid base plates that fan out around the rear of the trailer door (and may collapse flat to facilitate lo ading/unloading), and bladde rs that attach to the rear of the trailer and inflate once the vehicle is at cruising sp eed. A number of variations on these designs have been considered. For exampl e, a number of tests have been conducted on the optimum angle for base plate designs [TMA 2006, Storms 2004, Salari 2006].
There is relatively strong agreemen t in the literature as to the benefit of boat tail designs. Fuel consumption benefits are generally estimated to range from 4 to 6 percent, and C D benefits range from 6.5 to 9 percent. (One study did show C D benefits ranging from 14 to 19 percent, but this was based on a scale model wind tunnel test and appears to be an outlier [Storms 2004]).

Boat tail costs were estimated from several di fferent sources, with pr ices ranging from $1,500 to $2,000 [Site Visits, AT Dyanmics, Schubert 2008].

4.2.2.6 Other Aerodynamic Drag Reduction Approaches
A number of additional appro aches to reducing vehicle drag have been proposed. These approaches include:

• Active flow conditioning, which uses pneumatic blowing to equalize pressure along the vehicle surfaces [Englar 2004].

• Fully skirted wheels

• Extreme reshaping of the tractor or trailer

• Replace side mirrors with monitors
While these may be promising, it does not appear that they are viable strategies over the time horizon of our analysis. This is due either to technical complexit y, or regulatory or operational barriers.4-49 4.2.2.7 Challenges to Deployment of Trailer Aerodynamics
There are number of challenges to widespread deployment of traile r aerodynamic devices.

• On average, fleets operate three trailers fo r every one tractor and have optimized their operations to take advantage of multiple trailers per tractor. Without a change to the operations side of freight movement, operators would need to outfit th ree trailers for each tractor, effectively multiplying the capital cost by three.

• “For hire” motor carriers (as distinguished fr om private fleets) do not necessarily own the trailers that they transport, which are often owned by the shipper. Because the motor carrier captures the windfall fuel savi ngs that accrue from improve d aerodynamics, the shipper has little incentive to invest in fuel efficiency.

• Tractor trailers must conform to federal size a nd weight restrictions to travel on interstate highways. These restrictions are not necessarily relaxed for trailer aerodynamic devices (although some waivers have been granted on a limited basis). Add-on devices may add to trailer length (as in the case of a boat tail), wi dth (as in the case of wh eel fairings, which are not currently offered on the market), and weight . The weight issue is exacerbated if snow and ice collect under the side skirts, which has been an issue in some fleet trials [Site Visits].

• Durability: There is some concern as to whet her devices can withstan d the rigors of a linehaul operational service life. Fo r example, side skirts can be damaged by obstacles on the ground, and a boat tail may be damaged if deployed when a truck backs into a loading area.

• Trailer aerodynamic devices are not currently standard equipment. Using them in a fleet requires seeking out and purchasing them from a third party vendor and installing them as a retrofit. Device manufacturers claim that typi cal installation time is approximately 6 manhours. 27

• Trailer aerodynamic devices are not universally deployable on all types of trailers. The devices discussed above are intended primarily for box trailers, although side skirts could likely be implemented on many diffe rent trailer configurations.
4.2.2.8 Combined Tractor trailer Aerodynamic Packages
As discussed previously, the benefits of aer odynamic drag improvements are not additive. As such, it is important to directly test specific packages of devices to accurately estimate the combined aerodynamic drag reduction. To facilitate comparisons between different studies, trailer aerodynamic packages were categorized as e ither “partial aero pack ages”, or “full aero packages”.
Partial aero packages would generally include some side skirting and either a gap treatment or a boat tail.

27 Aero device manufacturer websites [Laydon, AT Dynamics]4-50 Such a partial package is estimated by Smartway [2009a] to offer a 5 percent fuel consumption benefit. In the NESCCAF/ICCT report [2009], Sw RI modeled a similar package and calculated approximately a 6 percent benefit 28 . Other tests of similar pack ages show fuel consumption benefits ranging from 4 to 6 percent [Fre ight Wing 2009, TMA 2006, Yatsko 2006, Site Visits]. These results would suggest reductions in C D on the order of 10 to 12 percent, although the one test that measured drag directly for a partial package estimated a 17 percent drag reduction. This result is closer to the results seen for a fu ll package and hence is considered an outlier.
A full aero package includes a full side skirt th at rides low to the ground, a boat tail, and a gap treatment. Packages similar to this have been te sted in a number of different contexts. The drag reduction benefit of a full aero p ackage is estimated to range fr om 17 percent up to 23 percent. There is greater variation in the measured fuel consumption benefit of these packages, which range from 6 to 11.5 percent [TMA 2006, Le uschen 2006, FreightWing, Marinko 2009, Salari 2009]. Strikingly, results from testing of an aer odynamic trailer by International Trucks in partnership with Wal-Mart showed wide variation between Wal-Ma rt’s initial evaluation of the vehicle and International’s fina l testing after making minor modi fications to the vehicle (11.5 percent) [TMA 2006]. All of the referenced sources appear ed to use a robust methodology and offer credible results. Given the number of C D tests that all show drag benefits on the order of 17 to 23 percent, the fuel consumpti on benefit of the full package is estimated to range from 8 to 10 percent.
Synthesizing the results from our analysis of the tracto r and of the trailer gi ves results as shown in Table 4-26. It appears feas ible to reduce total vehicle drag on the order of 22 to 24 percent using approaches and design modifica tions that are on the market or are expected to be offered in the next several years. It seems likely that ac hieving benefits that go significantly beyond these levels would likely require implementing some of the approaches detailed in Section 4.2.2.6.

Table 4-26. Tractor trailer aerodynamic packages

Tractor Trailer Estimated C D % Improvement
No aero Standard trailer 0.79 to 0.8 29 -22 to -25% Baseline (Smartway) Standard trailer 0.59 to 0.6 —
Baseline (Smartway) Partial aero package (Smartway) 0.52 to 0.53 10 to 12%

Improved Baseline Partial aero package (Smartway) 0.49 to 0.51 15 to 17% (6% add’l benefit )
Improved Baseline Full aero package 0.45 to 0.47 22 to 24% 30 (8% add’l benefit)

28 The results presented for “Package 2” in the NESCCAF/ICCT stud y include a full Smartway tractor + Smartway trailer, which is assumed to reduce C D to 0.5. The SwRI modeling showed that this package gives an 8 percent fuel consumption benefit. However, the baseline tractor is a partial Smartway configuration. The 6 percent bene fit referenced above assumes that ~25 to 30 percent of the drag reduction is applied to the tractor (to reduce C D to 0.59-0.60), and the rest is applied to the trailer.

29 Leuschen 2005

30 Assumes C D benefit of full trailer package is 17 to 19 percent4-51 4.2.3 Straight Box Truck Aero
Straight box trucks can leverage many of the same design features as comb ination tractor trailers to improve aerodynamics. A summary of potential op tions is included in Table 4-27. However, adoption of these design features is fairly uncommon. This low adoption rate is due to a combination of the lower average speeds, wh ich decrease the fuel savings benefit of aerodynamic devices, and lower annual mileage, which increases the time to payback.

Table 4-27. Straight box truck aerodynamic technologies
Technology % FC Benefit C D Improvement Capital Cost Status

Aero Devices Roof Deflector 2 to 3% 7 to 7.5% $500 to $800 Available Chassis Fairings 0.5 to 1% 2.5 to 3% $400 to $500 Not Available Box Skirts 2 to 3% 4.5 to 5% $500 to $1,000 Demos Box Fairing 0.5 to 1% 2.4 to 2.7% $500 to $650 Available Cab Streamlining 1 to 2% 5 to 6% $750 Available

Aft Box Taper 1.5 to 3% 7.6 to 8% $1,000 Not Available Aero Packages
Combination of Straight Truck Aero 5 to 8% 20% $3,000 to $3,500 Not Available

Options for improving the aerodynamics of these vehicles include the following:

• Roof deflectors : Simpler versions of the roof fairings which are common in combination vehicles. These devices are offered by OEMs but have a relatively low adoption rate. In addition, because they are not part of a sta ndard package, there can be an additional installation cost. Capital costs are base d on data provided during site visits.

• Fuel tank fairings : Similar to those available for trac tor trailers. The fuel consumption benefits are based on information furnishe d during site visits; the capital costs are estimated to be similar to the low-end of cost estimates for the tractor trailers. To our knowledge, these devices are not currently offered.

• Box skirts : Similar to the side skirts that are o ffered for combination trucks. At least one company offers a modular skirt design that can be used on straight trucks [Laydon 2009]. The benefits of box skirts are based on in formation gathered on site visits and information from the Laydon composites web site. Capital costs for this device are estimated to be half that of similar devi ces that are intended for tractor trailers.

• Aft box taper : This is a similar concept to that of a boat tail in a combination truck. It could entail actually molding the trailer box to provide better exit flows or an add-on device. To our knowledge, no one is actively pursuing this approach. Estimated benefits4-52 are based on discussions during si te visits; costs are assumed to be similar to that of the low-end tractor trailer estimate.

• Nose cone or box front fairing : Similar to the trailer gap fairings that attach to the trailer front that were discussed in reference to combination trucks. These devices may offer significant drag reduction benef its on straight trucks, as the roof top deflectors do not fully integrate air flow with the rest of th e truck. Capital costs are based on information from the Nose Cone [2009] website and from discussions with a truck dealer [Merrill 2009]; benefits are based on information furnished during site visits.

• Cab streamlining : In addition to the above strate gies, many of the same tractor body streamlining approaches that have already been adopted into the trac tor trailer fleet may be implemented in box trucks. These appro aches include sloped hoods and windshield, aerodynamic mirrors, and aerodynamic bumpers. Capital costs and be nefits of these design modifications are estimated based on information from Vyas [2002], which includes a similar list of modifications, but applies them to a tractor trailer.
We are not aware of any studies that have looked at combinati ons of devices for straight box trucks. However, multiplying the results suggests a maximum technical potential on the order of 25 to 30 percent reduction in C D . 31 Given that the drag reduction be nefit of these technologies is not additive, the likely C D benefit of all of the above approa ches taken in combination is on the order of 20 percent, at a cost of appr oximately $3,000 to $3,500. Assuming that the fuel consumption benefit is about 25 percent that of the C D for a vehicle with average speed of 30 MPH, the total fuel consumption benefit of th e total package is on the order of 5 percent. A vehicle that operates more freque ntly at higher speeds (average speed of 45 MPH) would see fuel consumption benefits be tween 7 and 8 percent.

4.2.4 Motor Coach
Because of their frequent high speed operation, motor coaches may benefit significantly from aerodynamic drag reduction. However, there is limite d information available in the literature and little additional data provided dur ing site visits that speak dire ctly to motor coach aerodynamics. As such, our estimates of motor coach aer odynamic drag reduction po tential are based on extending results of the line-haul anal ysis to the motor coach segment.

31 This is the result that is obtained if (1 – FC benefit) of each line item in the technology is multiplied together.4-53 Table 4-28 summarizes our estimates of motor coach aerodynamic improvements.

Table 4-28. Motor coach aerodynamic technologies
Technology FC Benefit C D Improvement Capital Cost Status

Boat Tail 4 o 6% 6.5 to 9% $1,500 to $2,000 Not Available
Vehicle Streamline 3 to 4% 6 to 8% $2,750 Not Available Aero Packages
Combination of Motor Coach Aero 7 to 10% 13 to 15% $4,250 to $4,750 Not Available

The following approaches were considered for op timizing the aerodynamics of the tractor trailer: cab streamlining, boat tailing, underbody treatments , gap treatments, wheel fairings, removing the mirrors, and active flow contro l. Of these, gap treatments ar e clearly not applicable. Given the already-low ride height, skirts and under body treatments likely do not offer a significant benefit. Active flow control has not yet been demonstrated; moreover, it is most beneficial on streamlined, as distinguished from bluff, bodies [Salari 2009].
Of the remaining options, cab streamlining and bo at tailing would appear to offer the best prospects for reducing aerodynamic drag. Boat tail ing on a tractor trailer is assumed to reduce drag by 6.5 to 9 percent and offer fuel consumpti on benefits of 4 to 6 percent. Additional cab streamlining in the line-haul segment is estima ted to reduce drag by 6 to 8 percent and reduce fuel consumption by 3 to 4 percent. In combin ation, these approaches would reduce drag by 13 to 15 percent and could offer a 7 to 10 percent re duction in fuel consumpti on. It is assumed that these benefits come at similar cost to those assumed for the line-haul segment: $2,750 for streamlining and $1,500 to $2,000 for boat tailing.

4.2.5 Class 2b Pickups and Vans
The potential for aerodynamic drag reduction in the Class 2b segment is estimated based on analysis conducted during the NHT SA rulemaking for the light-duty CAFE standard published in 2009. Although the NHTSA analysis extends only to Class 2a vehicles (<8500 GVW), it is assumed that similar aerodynamic improvements can be implemented in Class 2b. In general, Class 2b vehicles have a similar fo rm factor to their lighter counter parts that were considered in the NHTSA rulemaking, which suggests that this is a reasonab le approximation.

Table 4-29 summarizes our es timates of aerodynamic improvements in Class 2b vehicles.

Table 4-29. Class 2b pickup and van aerodynamic technologies

Technology FC Benefit C D Improvement Capital Cost Aero streamlining 3% 10% $60 to $1164-54 The NHTSA rulemaking considers a similar list of approaches to those discussed previously relative to tractor streamlin ing in line-haul vehicles [Pg 327–330]. These include underbody treatments; streamlined hood, windshield, fenders, and grill; reduced ride height (analogous to trailer side skirts); low drag side mirrors; optimized air flow pathways; and wheels or wheel wells. In combination, the NHTSA rulemaking assumes that a 10 percent reduction in C D is feasible. For heavier trucks, this level of drag reduction is as sumed to offer a 3 percent fuel consumption benefit.

These benefits are estimated to range from $60 to $116 in added co st. These cost estimates were applied independent of vehicle cl ass, so no adjustment was applie d to translate these to Class 2b vehicles.

4.3 Tires and Wheels

4.3.1 Overview
According to the 21 st Century Truck vehicle energy aud it discussed in Chapter 2, rolling resistance accounts for 13 percent of energy used in a Class 8 tractor tra iler at 65 MPH; 9 percent in a medium-duty vehicle at 40 MPH; and 5 perc ent in a transit bus tr aveling on the CBD duty cycle [DOE 2000]. Losses due to rolling resist ance are higher for heav ier vehicles and for vehicles traveling at higher speeds. The influe nce of vehicle speed on rolling resistance is illustrated in Figure 4-13. These losses may be mitigated by using lower rolling resistance tires and by adequately maintaining tire pressure while th e vehicle is in use. This chapter will describe technologies that are available or forthcomi ng which reduce losses due to vehicle rolling resistance. Following this overview of technologies, we will discuss how these technologies apply to different vehicle classes.

Figure 4-13. Influence of rolling resistance and aerodynamic drag on vehicle power demand as a function of speed4-55 4.3.2 Technologies for Reducing Rolling Resistance
4.3.2.1 Low Rolling Resistance Tires
Tire manufacturers are continually refining tire characteristics to reduce rolling resistance while maintaining tread life and safety. Low rolling resi stance tires include conventional duals with a lower C RR , and wide base singles (WBS) or “super si ngle” tires. Wide base singles reduce weight (about 50 lbs per tire) and can offe r lower rolling resistance than duals. They are often deployed in combination with aluminum wheels, which save an additional 40 lbs per wheel [Merrill 2009]. As part of data gathered for the NESCCAF/ICCT study [2009], it was estimated that a typical set of standard duals has an average C RR of 0.0068, while a set of low rolling resistance wide base singles on tractor and tr ailer has an average C RR of 0.0055, an improvement of 19 percent. Michelin provided data to the committee that sh owed the variation in rolling resistance for different types of tires (Figure 4-14) [Bradley 2009]. Based on this information, our baseline Class 8 tractor trailer is assumed to use steel-rimmed duals with a C RR of 0.0068. The methodology for extending these results to other ve hicle classes is discussed in Section 4.3.3.

Figure 4-14. Range of C RR for currently available tires [Bradley 2009]

Estimates of the capital costs and fuel efficiency benefits of low rolling resistance (wide-base single and dual) tires vary widely. Some of the reasons for this variance are as follows:

• It is unclear what the baseline for estimate s is. Sources judge the improvement from low rolling resistance tires relativ e to a previous generation tir e – which is itself a moving target given continuing improvement.

• Wide-base single tires are not necess arily low rolling resistance tires.

• Benefits vary widely depending on duty cycle and vehicle weight: grossed out vehicles will see a greater benefit than cubed out vehicles. Example Range of Rolling Resistance Coefficients for Heavy Truck Tires

0 2 4 6 8 10 12Rolling Resistance Coefficient, kg/T

Steer Drive Trailer Wide-base Single (NGWBST) EPA SmartWay tire thresholds4-56 The fuel efficiency benefits of low rolling resi stance dual tires were estimated to range from 2 percent to 7 percent [Smartway 2004a, Frey 20 07, Site Visits, Michelin 2009]. It is possible that the high end of this range corresponds to a relatively high rolling resist ance tire used for the baseline, as well as differences in duty cycle. As such, we have es timated the benefits relative to an average tire at 2 to 3 percent. Estimates for the cost of low rolling re sistance duals range from cost-neutral to $550 [Site Visits, Frey 2007] to re place all 18 tires. This equates to $30 per tire. We have used this higher estimate in the tec hnology matrix. These tires are widely adopted and provide rapid payback. However, some users have been reluctant to use low rolling resistance tires on cold weather routes due to safety concerns about less traction.
Estimates for the fuel efficiency benefit of wide -base singles range from 2 percent to upwards of 10 percent. One reason for the wi de range is that some estimates assume that WBS tires are installed only on the tractor, whil e others assume that they are installed on the tractor and the trailer; other reasons incl ude differences in duty cycle and diff erent dual tires used as a basis for comparison. Data gathered by Oak Ridge National Labs sheds some light on this issue: they performed a year-long study of fuel use across a cross-sect ion of tractor trailers using dual tires and WBS tires in different confi gurations (i.e., tractor only, trai ler only, tractor+trailer, and no WBS tires). They found fuel savi ngs of 6.5 percent for WBS on th e tractor only, and 9.2 percent on the tractor + trailer [Davis 2008, Table 5.10]. Based on a loose consensus of these different estimates, we estimate that the fuel efficiency of wide-base singles ranges from 3 to 6 percent on the tractor only, and from 6 to 9 percent on the tractor + trailer. We received cost estimates for WBS tires that ranged from cost-neutral to $1,800 for a set of four tires and wheels [Site Visits, Merrill 2009, Smartway 2004a, Schubert 2008]. Our final estimate is based on information received from an actual dealer [Merrill 2009], who quoted $900 for four tires plus four aluminum wheels (tractor only).

There are a number of issues th at preclude full adoption of WBS tires. These include reports of increased tread wear and susceptibility to damage on urban routes; inability to “limp” home on a flat, as one can do with duals; and lack of ava ilability in the event of a flat. It was suggested during the course of the s ite visits that tire makers are contin uously refining their treads, and endusers are willing to continue testing to see if the durability issues are addressed. It was also suggested that some systems – such as WBS spare tire systems and auto-inflate devices – enable further deployment of WBS.
As part of the NESCCAF/ICCT study [2009], th e steering committee concluded that a “next generation” WBS tire could achie ve a rolling resistance of 0.0045. Modeling by SwRI showed that this level of C RR offers an additional 5 percent bene fit relative to the current low rolling resistance WBS (C RR = 0.0055). This would suggest that th ese future WBS tires would reduce fuel use by 11 to 14 percent relative to the baselin e duals. In a similar vein, we estimated that future conventional duals will also improve offeri ng an additional 2 percent fuel savings relative to today’s low rolling resistance dual tires.

Our estimates for Class 8 tractor trai ler tires are summari zed in Table 4-30.4-57 Table 4-30. Assumed tire characteristics for class 8 tractor trailers

Tire Options Avg C RR C RR Imp. FC Benefit Standard Duals Package 0.0068
Low rolling resistance duals 0.0061 to 0.0062 (Est) 10% 2 to 4%
Wide base singles (WBS) (Tractor Only) 0.0055 19% 3 to 6%
Wide base singles (WBS) (Tractor + Trailer) 0.0055 19% 6 to 9%
Next generation WBS 0.0045 34% 11 to 14%

4.3.2.2 Pressure Monitors and Auto-Inflation Systems:

It is estimated that underinflate d tires decrease fuel consumption by 0.5 to 1 percent for every 10 psi of under inflation, with hi gher penalties corres ponding to more heavily loaded vehicles [Cummins 2007, Smartway 2004b]. Feedback offered from a number of s ources on site visits suggested that on average, vehicles run 10 to 20 psi under-inflated. Arvin Meritor presented information from a study that found that over half of tires on combination trucks were at least 5 psi under inflated, and 22% of tr ucks have at least one tire unde rinflated by over 20 psi [Hicks 2009]. These data suggest an average penalty of 0.5 to 2 percent due to u nder-inflated tires. Frey [2007] estimates a 0.6 percent benefit; reviewers generally felt this wa s a credible estimate, although published information from Wal-Mart estimat es benefits for their fleet at 1 to 3 percent [Yatsko 2007], and Arvin Meritor estim ates a 1% benefit [Hicks 2009].
Both tire pressure monitors and full auto-inflate systems are currently available for both trucks and trailers. Tire pressure monitor systems simply alert drivers if tire pressures are low; automatic tire inflation (ATI) systems actually maintain recommended tire pressure.
We received wildly divergent estimates as to the cost of these systems. Smartway estimates that an ATI system for a truck’s drive axles and trailer costs $900 [Smartwa y 2004b], while feedback from one site visit suggested a cost of $13,000. It was suggested that the Smartway estimate might be reasonable for an inflation monitor but was far too low for an ATI on a tractor. As a third data point, Arvin Meritor presen ted data to the committee describing a trailer ATI system that sells for $300 to $400 [Hicks 2009]. Subsequent discussions suggested that the cost of a trailer inflation system is far lower than a tr actor tire inflation sy stem but that $4,000 to $5,000 might be a more a reasonable estimate. Based on this feedback, we have estimated capital costs and benefits for three different systems: a tracto r based ATI, a tractor ba sed monitoring system, and a trailer-based ATI (Table 4-31).
Nitrogen-filled tires were also mentioned as a potential strategy for ma naging pressure. Using nitrogen reduces the amount of mo isture in the tire, which can k eep the tire from heating up and over-inflating. We did not have enough info rmation to characterize this strategy.4-58 Table 4-31. Tire pressure monitoring and inflation systems
System Capital Cost Benefit Tractor tire monitor $900 [Smartway 2004b] 0.6% Tractor ATI $4,000 to $5,000 [Site Visits] 0.6% Trailer ATI $300 to $400 [Hicks 2009] 0.6%

4.3.3 Application of Tire and Wheel Technology to Different Vehicle Classes
As discussed previously, the effect of rolling resistance on vehicle fuel use varies depending on vehicle application. Because low rolling resistan ce offers the most benefit at high speeds and vehicle weight, most of the information that was available and discussed above applies to Class 8 tractor trailers. To extend these results to other vehicle classes, we have scaled results according to the 21 st Century Truck energy audit discussed in Chapter 2 [DOE 2000]. As discussed previously, according to this audit, rolling resistance accounts for:

• 13 percent of energy used in a cla ss 8 tractor trailer at 65 MPH;

• 9 percent in a medium duty vehicle at 40 MPH; and

• 5 percent in a transit bus trav eling on the CBD duty cycle.

Based on these estimates, we have scaled the bene fit estimated for a Class 8 tractor trailer data for different applications as s hown in Table 4-32, with appropriat e adjustments made for vehicle weight. It should be stressed that an accurate estimate of these parameters will require actual drive cycle modeling for different vehi cle applications and duty cycles.

Table 4-32. Rolling resistance scaling parameters

Vehicle Class Estimated contribution of Rolling Resistance to energy losses Rel. Efficacy of Rolling Resistance Tractor trailer (65K lbs) 13% 1.0
Motor Coach 9% 0.7
Box and Bucket 9% 0.7
Transit Bus 5% 0.4
Refuse 8% 0.8

4.3.3.1 Tractor Trailers
Currently, 5 to 10 percent of us ers use wide-base single tires, and an additional 60 percent specify a low-rolling resistance tire. Market pe netration of WBS tires is challenging due to concerns over flat tires and tr ead-wear as discussed above. A su mmary of our assumed benefits for tractor trailer tire and wheel t echnologies is included in Table 4-33.4-59 Table 4-33. Class 8 tractor trailer tire and wheel technologies
System Capital Cost FC Benefit Low rolling resistance dual $30 per tire 2 to 3% Wide base single (WBS) with aluminum wheels – Tractor only $900 ($225 per tire + wheel) 3 to 6%
Wide base single (WBS) with aluminum wheels – Tractor + 1 Trailer a $1,800 6 to 9%
Next-generation dual $30 per tire 4 to 5% Next-generation WBS (Tractor Only) $900 8 to 11% Next-generation WBS (Tract or+trailer) $1,800 11 to 14% Tractor tire monitor $900 0.6% Tractor ATI $4,000 to $5,000 0.6% Trailer ATI $300 to $400 0.6%

a For 3 trailers, this cost goes to $3,600

4.3.3.2 Motor Coaches
Motor coaches can benefit from low rolling resist ance tires, wide base singles, or automatic inflation systems. Wide-base singles are availabl e for motor coaches, but we do not believe that they are widely deployed. There is only a single axle on a motor coach that uses dual tires (and hence can take advantage of a WB S). Benefits are estimated from the Class 8 tractor trailer and are scaled using a factor of 0.9 to account for differences in duty cycle and weight. A summary of motor coach tire and wheel fuel consumption technologies and benefits is included in Table 4-34.

Table 4-34. Motor coach tire and wheel technologies
System Capital Cost FC Benefit Low rolling resistance dual $30 per tire 1.4 to 2.1% Wide base single (WBS) $450 ($225 per tire + wheel) 2.1 to 4.2% Next-generation dual $30 per tire 2.8 to 3.5% Next-generation WBS $450 5.6 to 7.7% Tire monitor $900 0.42% ATI $4,000 to $5,000 0.42%

4.3.3.3 Class 3-6 Box and Bucket Trucks
Class 3-6 Box trucks gain some benefit from low rolling resistance duals and potentially from wide-base singles. WBS tires face a steep challeng e in this application, due in large part to concerns over tread life and tire wear (e.g., side wall damage) [Site Visits ]; that said, WBS tires4-60 are available for this application and could gain ma rket share on regional ro utes – particularly if future version improve tread life. Inflation mon itors could possibly come into this segment; full ATI systems are unlikely due to high cost. Benefits are estimated from the Class 8 tractor trailer and are scaled using a factor of 0.7 to account for differences in duty cycle and weight. A summary of box and bucket truck tire and wheel fu el consumption technologies and benefits is included in Table 4-35.

Table 4-35. Class 3-6 box and bucket truck tire and wheel technologies
System Capital Cost FC Benefit Low rolling resistance dual $30 per tire 1.4 to 2.1% Wide base single (WBS) $900 ($225 per tire + wheel) 2.1 to 4.2% Next generation dual $30 per tire 2.8 to 3.5% Tire monitor $900 0.42%

4.3.3.4 Urban Transit Buses
Transit buses gain only minor benefit from low ro lling resistance tires, a nd they are unlikely to adopt wide base singles. We ha ve also included inflation mon itors as a potential technology for this application. Benefits are estimated from the Class 8 trac tor trailer and are scaled using a factor of 0.4 to account for differences in ve hicle duty cycle. A summary of box and bucket truck tire and wheel fuel consum ption technologies and benefits is included in Table 4-36.

Table 4-36. Transit bus tire and wheel technologies
System Capital Cost FC Benefit Low rolling resistance dual $30 per tire 0.8 to 1.2% Next generation dual $30 per tire 1.6 to 2% Tire monitor $900 0.25%

4.3.3.5 Refuse Haulers
Refuse haulers, like transit buses, gain only minor benefit from low rolling resistance tires and are unlikely to adopt wide base si ngles. Benefits are estimated from the Class 8 tractor trailer and are scaled using a factor of 0.6 to account for differences in vehicl e duty cycle. This scale factor reflects the low speed duty cycle (which reduces the impact of rolling resistance), and high weight (which increases the impact). A su mmary of refuse hauler tire and wheel fuel consumption technologies and benef its is included in Table 4-37.4-61 Table 4-37. Refuse hauler tire and wheel technologies
System Capital Cost FC Benefit Low rolling resistance dual $30 per tire 1.2 to 1.8% Next generation dual $30 per tire 2.4 to 3% Tire monitor $900 0.36%

4.3.3.6 Class 2b Pickups and Vans
Rolling resistance opportunities for Class 2b ve hicles are estimated from the NHTSA study. NHTSA does not include low rolling resistance ti res as an option for its large truck segment. Although they are technically feas ible, the rulemaking deems that there are issues with adoption due to traction and handling requirements at pa yload and towing limits. We have included the NHTSA estimates for light-duty applications with the caveat that these issues may preclude the adoption of low rolling resistance tires in this segment. The NHTSA rule estimates a 10 percent reduction in tire rolling resistance ; for this applicati on, it is estimated that a 10 percent reduction in C RR reduces fuel use by 1 to 2 percent. Cla ss 2b tire and wheel technologies are summarized in Table 4-38.

Table 4-38. Class 2b tire and wheel technologies System Capital Cost FC Benefit Low rolling resistance tires $6 to $9 1 to 2%

4.4 Weight Reduction

4.4.1 Overview
The size of medium- and heavy-duty vehicles is dictated by the vehi cle’s mission. Unlike the light-duty sector, where larger vehicles ar e often a luxury, reducing weight by downsizing vehicles is not a viable option for the medium- and heavy-duty sector.
Weight can be reduced in medium and heavy-duty vehicles by s ubstituting new, lighter weight materials. Potential material substitutes include high-strength steel, aluminum, or composites. Weight reduction is of benefit to truck operators for several reasons:

• In grossed-out vehicles, it offers a productiv ity benefit, which can save fuel by allowing shippers to increase the am ount of cargo per truckload.

• In smaller heavy-duty vehicles, keeping weight under 33,000 lbs avoid a $12,000 federal excise tax.

• In all vehicles, reducing wei ght reduces the vehicle’s road load, thereby saving fuel.4-62 The fuel efficiency benefit of material subst itution varies by duty cycl e and by application. In general, weight reduction is most effective over urban drive cycles that feature a lot of braking and low road speeds. Data from Helms [2003] shows that on a city duty cy cle, 89 percent of the vehicle’s road load is weight dependent, co mpared to 38 percent on a steady-state 55 MPH duty cycle, and 25 percent on a steady state 75 MPH duty cycle.
Estimates of capital costs and benefits rely primarily on a study conducted by the Institute for Energy and Environmental Resear ch (IFEU) [Helms 2003] and on information presented to the committee by the Aluminum Association [Alcoa 2009]. This information is supplemented with information gathered on site visits and additional sources from the literature.
This section presents estimates for the capital cost s and fuel efficiency benefits of varying levels of weight reduction for each of the different vehicl e classes. The benefits of weight reduction are presented in terms of “% fuel saved per 1,000 lbs of weight reducti on”, except for Class 2b vehicles, which present savings in terms of “% fuel saved per 3 per cent weight reduction”. Capital costs are expressed in dollars per lb, with increasing costs as the amount of weight removed rises. Following discussion of capital costs and benefits for each vehicle class, we discuss historic trends and the effect of fuel efficiency and emissions control technologies on vehicle weight.

4.4.2 Class 8 Tractor Trailer
The benefits of weight reducti on for Class 8 tractor trailers vary depending on whether the application is weight-constrained (“grossed out ”) or volume-constraine d (“cubed out”). For weight-constrained vehicles, any we ight that is removed from th e truck can be replaced with additional cargo, leading to fewer truck-miles. We have assumed that this offers a fuel consumption benefit that is equal to the extr a cargo. For a 35,000 lbs truck that carries 45,000 lbs of cargo, reducing weight by 1,000 lbs increases ca pacity, and hence reduces fuel consumption, by 2.2 percent 32

. For cubed-out vehicles, the benefits of weight reduction relate dire ctly to fuel savings. A number of sources in the literature provide estimates as to the efficacy of wei ght reduction in Class 8 tractor trailers. These estimates range from a low of 0.17 pe rcent savings per 1,000 lbs of weight reduction to a high of 1.25 percent savings per 1,000 lbs of weight reduction. One reason for this variance is differences in the duty cycle – ty pically higher numbers correspond to regional or urban routes. A number of studies congregate in a middle range that varies from 0.4 to 0.6 percent fuel savings per 1,000 lbs [Alcoa 2009, Helms 2003, Cumm ins 2007, NESCCAF 2009, Smartway 2004d]. The feedback from reviewers on site visits generally suggested that this was a reasonable estimate of the weight savings benefit.
The Aluminum Association [Alcoa 2009] presente d data to the committee that indicates that 3,500 lbs of weight reduction is a viable target for Class 8 tracto r trailers using approaches as

32 In their presentation to the committee, the Aluminum Associat ion [Scheps 2009] sited data that suggests 0.55 percent fuel sav ing for 1 percent weight reduction, or 0.69 percent savings per 1, 000 lbs in an 80,000 lb vehicle. It is not clear why this number is so low for a weight-constrained application.4-63 illustrated in Figure 4-15. Alcoa has published data showing a roadmap to achieve 3,500 to 4,500 lbs of weight reduction, as shown in Figure 4-16. Other weight saving s features that are

Figure 4-15. Tractor trailer weight reduction opportunities [Alcoa 2009]

Figure 4-16. ALCOA estimates of weight-saving opportunities for tractor trailers [Scheps 2008]4-64 not included in these figures, but were pointed out during site visits include disc brakes, lightweight brake drums, and wide base single tires.
Capital costs were estimated based on feedback from the Aluminum Association presented to the committee. During this discussion, it was suggested that there ar e a series of weight reduction opportunities that cost $2 to $4 per lb which ar e or have been adopted into vehicles. This includes lightweight cab structure, fuel tank s, HVAC components, bell housing, and aluminum wheels. Data from Smartway references lightwe ight tractors and traile rs that are currently available that saves 1,000 to 2,000 lbs at a cost of $1 to $2 per lb. Given that many of these lightweight technologies have al ready been adopted, we opted to use the higher range cost estimate for the “low cost” weight reduction opport unities. This is followed by a tier of weight reduction that costs $4 to $8 per lb for which adop tion rates are on the orde r of 10 percent, such as a lightweight 5 th wheel and landing gear. Finally, the hi ghest cost options considered tend to cost $8 to $10 per lb. 33 We used this information to establis h three cost tiers to achieve a 3,500 lb weight reduction. Results ar e summarized in Table 4-39.

Table 4-39. Weight reduction capital cost and benefit for volume-constrained class 8 tractor trailers
Weight Reduction Cost Fuel Savings (per 1,000 lb) 0 to 1,000 lbs $2 to $4 per lb 0.4 to 0.6% 1,000 to 2,000 lbs $4 to $8 per lb 0.4 to 0.6% 2,000 to 3,500 lbs $8 to $10 per lb 0.4 to 0.6%

4.4.3 Transit Bus
Given their low speed, stop-and-go duty cycle, tr ansit buses can benefit greatly from weight reduction. Data on the benefits of weight reduc tion in this segment are sourced from the Aluminum Association’s presentation to the co mmittee and the IFEU report. Estimates from the IFEU report range from 3.75 to 7.5 percent fuel sa vings for a 10 percent we ight reduction. These estimates apply to a 15 metric ton bus traveli ng on an urban, congested drive cycle. Data presented by the Aluminum Association estimate d fuel savings ranging from 5 to 8 percent per 10 percent weight savings from three different studies. Based on this data, we have used an estimate of 5 to 7.5 percent fuel savings per 10 percent weight reduction. For a 25,000 lbs bus, this equates to 2 to 3 percent fu el savings per 1,000 lbs of weight.
Data presented by Alcoa estimates that there is potential to save 3,000 to 3,500 lbs from an urban transit bus. Figure 4-17 shows an ill ustration of how to achieve this degree of weight savings. To estimate cost for this package, we applied the same costs as those estimated for the tractor trailer, but scaled the weight ranges to which these cost s apply based on the ratio of the tractor trailer weight to the bus weight. This approximation attempts to account for the fact that the tractor

33 We initially used estimates from Frey [2007] of $2,000 to ac hieve fuel savings ranging from 1 to 3 percent, but received feed back that this was too low of a cost. Using an elasticity of 0.5 percent per 1,000 lbs, this equates to $0.3 to $1 per lb.4-65 Figure 4-17. Weight savings realized for lightweight demonstration bus in China [Scheps 2008]

trailer is a heavier vehicle, and as such should be easier to shed weight. Given that the unloaded weight of our baseline tractor trailer is approx imately 35,000 lbs and the we ight of the transit bus is 28,000 lbs, we use a scale factor of 0.8 to yield the estimates shown in Table 4-40.

Table 4-40. Weight reduction capital cost and benefit for transit buses
Weight Reduction Capital Cost Fuel Savings (per 1,000 lb) 0 to 800 lbs $2 to $4 per lb 2 to 3% 800 to 1,600 lbs $4 to $8 per lb 2 to 3% 1,600 to 2,800 lbs $8 to $10 per lb 2 to 3%

4.4.4 Motor Coach
Estimates for the benefit of weight reduction in motor coaches are drawn from the IFEU report, which estimates 2.4 percent fuel savings per 10 pe rcent weight reduction. Data was estimated for an 18 metric ton vehicle traveling on a primarily highway duty cycle. Fo r a 36,000 lb coach, this fuel savings estimate equates to 0.7 percent per 1,000 lbs saved. Capital co sts are estimated using4-66 the same logic as that described for the trans it bus. We have assumed a 36,000 lb coach, which weighs approximately the same as a tractor traile r, so no scaling is needed. Table 4-41 shows our results for motor coaches.

Table 4-41. Weight reduction capital cost and benefit for motor coaches
Weight Reduction Capital Cost Fuel Savings (per 1,000 lb) 0 to 1,000 lbs $2 to $4 per lb 0.7% 1,000 to 2,000 lbs $4 to $8 per lb 0.7% 2,000 to 3,500 lbs $8 to $10 per lb 0.7%

4.4.5 Class 3-6 Straight Box and Bucket Trucks
Fuel savings for Class 3-6 Box and Bucket truc ks are estimated based on data from the IFEU report and data presented by the Aluminum Asso ciation. The Aluminum Association presented data that estimates 6.3 percent fuel savings per 10 percent we ight reduction for a 16,340 lb truck on the HTUF duty cycle. Because this is a simila r estimate to that of the transit bus from the same study, we have assumed the same 5 to 8 percent savings per 10 percent weight reduction that we use for the transit bus (for which ther e are more data). For a 16,000 lbs vehicle, this equates to 3 to 5 percent savi ngs per 1,000 lbs of weight reduc tion. Capital costs are estimated using the methodology described in the transit bu s section, and use a scale factor of 0.41. The results are shown in Table 4-42.

Table 4-42. Weight reduction capital cost and benefit for class 3-6 box and bucket trucks
Weight Reduction Capital Cost Fuel Savings (per 1,000 lb) 0 to 470 lbs $2 to $4 per lb 3 to 5% 470 to 940 lbs $4 to $8 per lb 3 to 5% 940 to 1,650 lbs $8 to $10 per lb 3 to 5%

4.4.6 Refuse Hauler
We are not aware of any data that estimates the benefits of weight reduction for refuse vehicles. As such, we have extended the estimates from the transit bus to the refuse vehicle. The logic for doing so is that they both trav el on highly urban routes that feature a number of stops. Applying our estimate of 5 to 8 percent fuel savings per 10 percent weight reductio n to a refuse hauler (assumed weight of 35,000 lbs) equates to a fu el savings of 1.4 to 2.3 percent per 1,000 lbs. Given that these vehicles require many high-strength elements, it is unclear to what extent lowcost weight reduction is viable . As such, we have assumed that only 2,000 lbs of weight reduction are feasible, and that these come at hi gher cost than those estimated for the tractor trailer, as shown in Table 4-43.4-67 Table 4-43. Weight reduction capital cost and benefit for refuse haulers
Weight Reduction Capital Cost Fuel Savings (per 1,000 lb) 0 to 2,000 lbs $4 to $8 per lb 1.4 to 2.3%

4.4.7 Class 2b Pickups and Vans
Weight reduction of Class 2b vehicles is estim ated based on data included in the NHTSA lightduty rulemaking. NHTSA considers up to 5 percent weight reduction a viab le target for large (5,000 lb GVW) light trucks. They estimate that a 3 percent reduction in weight gives a 0.6 to 0.9 percent reduction in fuel use. This weight redu ction is estimated to cost $1 to $2 per lb for 0 to 2 percent weight reduction, and $2 to $4 per lb for 2 to 5 percent we ight reduction. We have assumed that these estimates carry over to the he avier Class 2b vehicles as shown in Table 4-44.

Table 4-44. Weight reduction capital cost and benefits for class 2b pickups and vans
Weight Reduction Capital Cost Fuel Savings (per 3%) 0 to 2% $1 to $2 per lb 0.6 to 0.9% 2 to 5% $2 to $4 per lb 0.6 to 0.9%

4.4.8 Weight Increases
While this section has focused on weight reduc tion, a more pressing issue for industry is increased weight due to emissions technologies.
Emissions control systems, starti ng with low-rate EGR, moving to medium rates, and finally on to SCR systems, have added approximately 500 lb s to vehicle weight. In addition, many of the fuel savings technologies that are being considered add signifi cantly to vehicle weight. These include waste-heat recovery systems (200 to 300 lbs); hybrid-electr ic technology (400 to 1,000 lbs); hydraulic hybrids (~1,000 lbs); and aerodynamic treatment devices for trailers (750 lbs) and tractors (unknown, but perhaps 200 to 300 lbs). In combination, these technologies could add upwards of 2,000 lbs to vehicle weight, in addition to emissions control systems. As a group, fuel savings plus emissions technology could a dd 2,000 to 3,000 lbs to vehicle weight, as summarized in Table 4-45.4-68 Table 4-45. Weight penalty for fuel savings and emissions control

Vehicle Class Added weight (lb) Fuel Consumption Penalty Class 8 Tractor Trailer 2,000 to 3,000 1 to 1.5% Transit Bus 2,500 5 to 7.5% Motor Coach 2,000 to 3,000 1.4 to 2.1% Class 3-6 Box and Bucket 1,000 3 to 5% Refuse Hauler 1,500 2.1 to 3.5% Class 2b 500 to 1,000 2 to 3%

4.5 Transmission and Driveline

“Transmission and driveline” refe rs to, collectively, the system that connects the propulsion system to the wheels. It includes the transmi ssion, the final drive, and the axle. Options for realizing fuel efficiency benef its by optimizing the transmission and driveline generally fall into one of two categories:

• Improved driveline efficiency : Strategies that increase the efficiency of power transfer from the propulsion system to the wheels.

• Improved systems integration : Strategies that enable the engine to operate at higher average drive cycle efficiency. These appr oaches may have significant overlap with driver management and coaching st rategies and hybrid technologies.
Broadly speaking, a different se t of strategies applies to vehicles for which automatic transmissions are prevalent than those for wh ich manual transmissions dominate; to a lesser extent, the same is true for vehicles traveli ng on stop and go duty cycles than those operating primarily over the highway. We have identifi ed three different technology roadmaps, depending on the vehicle duty cycle and base line transmission technology:

• On-highway, manual transmission: Includes tractor trailers

• Urban, automatic transmission: Class 3-6 Box and Bucket, re fuse haulers, and urban transit buses

• On-highway, automatic transmission: Includes motor coach

• Mixed duty cycle, mixed technology: Class 2b
4.5.1 Tractor Trailer (On-highway, manual transmission)

The baseline tractor trailer is assumed to co me equipped with a 10-speed manual transmission with overdrive. Fuel savings approaches include reducing mechanical losses in the driveline itself, or improving powertrain integration to im prove the average engine thermal efficiency.4-69 Reducing mechanical losses in the driveline offe rs potential for 1.5 to 2.5 percent reduction in fuel consumption. Approaches id entified during site visits incl ude reducing driveline friction; using direct drive in top gear in stead of overdrive; and switching to one drive axle instead of two. Driveline friction may be reduced by using impr oved lubricants and materials, or by improving lubrication management. One approach that was discussed uses an active lube level control system to vary the amount of lubrication de pending on vehicle speed. At high speed, system inertia is great enough to overcome friction without lubrication. Under these conditions, lubrication actively contributes to driveline losses, so reducing lube levels provides an efficiency benefits. In total, driveline fric tion reduction is estimated to impr ove fuel efficiency by 1 to 1.5 percent. These friction reduction opp ortunities are estimated to range from cost-neutral (as in the case of incremental friction reduction) to $500 [Frey 2007].
Using a direct drive top gear in stead of overdrive, or switching to a single larger drive axle (instead of two smaller ones) can each improve driveline effici ency by reducing the number of mechanical connections. Benefits of direct drive were estimated to range from 1.5 to 2 percent at zero-cost. Using a single drive axle was estimated to improve driveline efficiency by about 1 percent at high speed. This approach also allows a vehicle to use lower rolling resistance tires, on the new non-drive axle, which may enable an ad ditional 1 to 2 percent benefit. We did not receive any information as to the cost of th is system; its implementation requires additional vehicle controls and modification of the vehicles suspension system [Site Visits]. We estimate that the cost of these upgr ades range from $200 to $300.
Improved integration of the drivelin e with the powertrain in a tractor trailer can raise the average efficiency of the engine over an actual real-w orld drive cycle. The lowest hanging fruit entails appropriately matching system gearing to the spec ific application. This process entails selecting a top gear and rear axle ratio that matches typical cruise speed (ensuring that the engine is in its peak efficiency window). These specifications vary from fleet to fleet; to th e extent that a vehicle purchaser knows the specific roads on which a truck will travel, systems can be highly optimized to match their application. C onversely, some purchasers simply use standard specs, or spec vehicles based on what they purchased in the past. As such, all of the major OEMs make a concerted effort to work with purchasing agents to properly manage the vehicle spec process.
Beyond appropriately spec-ing the ve hicle, there are several options for actively optimizing gear selection while in use. These in clude increasing the number of tran smission gears, or selecting an automatic manual (AMT) or automatic (AT) tran smission. Increasing the number of transmission gears offers only minor benefits for most line-haul applications. However, on some routes (such as through the mountains), increased transmission gearing can offer benef its of up to 5 percent [Site Visits]; however, this does not appear to be a major opportunity in this market segment. Adding additional transmission gears is estimated to add $1,000 [Global Insight 2004].
Both automatic and automatic-manual transmissions have some presence in this market segment. Based on information provided during site visits, we estimate penetration of these systems to be 5 percent and 10 percent, respec tively. AMTs and ATs both allow the vehicle to optimize gear selection to maximize engine e fficiency. Although ATs optimize g ear selection, they introduce an additional parasitic load to the driveline, wh ich decreases or negates the efficiency benefit. AMTs, which are simply manual transmissions with an automated mechanical shift schedule, achieve the shift optimization benefits of an AT without the accompa nying parasitic loads.4-70 Estimates of the fuel consumption benefits of AMT and AT technology vary widely – as low as 2 percent, and as high as 19 percen t [Detroit Diesel 2009b, Site visits]. This is due in large part to variations between drivers and duty cycles. Howe ver, feedback offered on site visits suggested that, on average, AMTs offer medi um single-digit FC benefits. As such, we have estimated the benefit of an AMT to range from 4 to 8 percent for an average driver at a cost range from $4,000 to $5,700 34 . However, it should be noted that the best, most well-trained driver with appropriate driving aids can approach the fuel efficiency benefits of an AM T, and some fleets have adopted this approach. Automatic transmissions are estima ted to range from 0 to 5 percent benefit. This range reflects variation due to both duty cycle and the level of driver training. An AT is estimated to cost $15,000. Capital cost estimate s are based on information provided during site visits and discussions with a dealer [Merrill 2009].
Table 4-46 summarizes the fuel consumption benef it, weight, and capital costs for tractor trailer driveline and transmission options.

Table 4-46. Driveline and transmission options for class 8 tractor trailers
Strategy % FC Benefit Weight Capital Cost Appropriate spec-ing 1 to 3% — — Friction reduction 1 to 1.5% — $0 to $500
Direct drive 1.5 to 2% — — Single drive axle 1% — $200 to $300 AMT 4 to 8% 80 lbs $4,500 to $5,700 AT 0 to 5% 200 lbs $15,000

4.5.2 Class 3-6 box and bucket, refuse haulers, and urban transit buses (urban, automatic transmission)
Class 3-6 straight box truc ks, bucket trucks, refuse haulers, an d urban transit buses all operate on a predominantly urban, stop-and-go duty cycle which re quires more shifts per mile than for other applications. Given the nature of this duty cycle, feedback offered during s ite visits suggest that automatic transmissions are appropriately matched to this segment. The entirety of the refuse truck and urban bus market currently use automa tic transmissions; it is estimated that about 70 percent of Class 3-6 box and bucket trucks also use ATs [Site Visits]. We have assumed that the baseline vehicle for these urban duty cycl es uses a 6-speed au tomatic transmission.
In these market segments, automatic power shift transmissions offer uninterrupted shifts, which gives increased vehicle dr ivability (which helps w ith driver retention), productivity, and in some cases, fuel efficiency. The productivity benefit is a result of the automatic transmissions offering better acceleration than manual or automatic-manua l transmissions (AMT). As such, they allow users with large numbers of stops to get their job done faster. In certain applications, this can

34 These estimates assume that the actual selling price is 0.6 times the list price furnished by manufacturers.4-71 save fuel. In addition, the smoother shifting associat ed with an AT allows the engine to run in a high efficiency regime more of the time, whic h can also offer fuel efficiency benefits.
Opportunities for improving the fu el efficiency of the assumed ba seline vehicle include friction reduction, reducing transmission parasitic losses , using more aggressi ve shift logic, and increasing the number of transmission gears. In addition, appropriately sp ec-ing the driveline can pay similar dividends to those obser ved in Class 8 tractor trailers in these market segments. Frey estimates that driveline friction reduction and tran smission parasitics can improve fuel efficiency by up to 1 percent at costs ranging from 0 to $500. Aggressive shift logic (ASL) and early lockup is estimated by NHTSA to offer 1.5 to 2.5 percent im provement in light-duty ve hicles at a cost of $59. Because it is not clear to what extent this is already employed in the medium and heavy duty sector, we have estimated the benefit for AS L to range from 0.5 to 1 percent at a cost of $100.

Estimated benefits of increasi ng the number of transmission g ears range from 1 to 5 percent [Walsh 2006, Site visits, NHTSA 2009], althoug h it is not always clear what the baseline assumptions are. The NHTSA light-duty regulati on estimates the fuel efficiency benefit of increasing from a 4/5 speed AT to a 6/7/8 speed AT to range from 2.7 to 4.1 percent. This would imply that the incremental benefit in going fr om a 6-speed to an 8-speed transmission is 1.4 percent for a light truck. This estimate may be low for applications such as package delivery vehicles, transit buses, or refuse trucks, which have a highly transient duty cycle. As such, we have used a mid range of the benefit estim ated in literature of 2 to 3 percent.
NHTSA estimates that increasing from a 5-speed to an 8-speed automatic transmission costs $638 for a 5,000 lbs GVW truck. Information available on company websites 35 includes a $405 up-charge to go from a 5-speed to 6-speed tr ansmission in a Class 2b Pickup. Given that the baseline vehicle uses a 6-speed, we estimate that the incremental cost of going from 6-speeds to 8-speeds in a large light-duty tr uck is $425. To extrapolate this estimate to different vehicle segments, we scaled this value by the engine torque for a standard baseline vehicle, as shown in Table 4-47.
Table 4-48 summarizes the fuel consumption be nefit and capital costs of various driveline options for refuse haulers, trans it buses, and Class 2b applications.

35 Dodge Ram website4-72 Table 4-47. Estimated capital cost of going from 6 to 8 speed automatic transmission

Vehicle Class Torque (ft-lb) Multiplier Capital Cost Class 2a truck (NHTSA estimates) 332 (5L gasoline) 1.0 $425

Class 2b pickup and van 365 to 750 (5.4L gas to 6.7L diesel) 1.1 to 2.3 $500 to 1,650

Class 3-6 truck 750 to 1,300 (6.7L to 9L) 2.3 to 3.9 $1,000 to $1,650

Transit Bus 850 to 1,300 (7.6L to 9L) 2.6 to 3.9 $1,100 to $1,650

Motor coach 1,450 to 1,700 (11L to 13L) 4.4 to 5.1 $1,870 to $2,200

Refuse 1,650 to 2,050 (13L to 15L) 5.0 to 6.2 $2,100 to $2,600

Table 4-48. Driveline and transmission strategies for refuse hauler, class 3-6 box and bucket trucks, and transit buses
Strategy % FC Benefit Capital Cost Appropriate spec-ing 1 to 3% — Aggressive Shift Logic and Early Lockup 0.5 to 1% $100 Reduced AT parasitics and friction reduction 1% $0 to $500 8-speed AT 2 to 3% See Table 4-47

4.5.3 Motor Coach (On-Highway, automatic transmission)
Motor coaches are unique in that they all use automatic transmissions but spend much of their time on the highway. This is because automatic tr ansmissions offer a smoother ride, which is important in a passenger-driven application. That said, European motor coaches tend to use manual or automatic manual transmissions. We have assumed the following to characterize transmission and driveline opportuni ties in the motor coach segment:

• Motor coaches generally use similar technologi es to those used by tractor trailers to improve driveline efficiency, but adopt simila r technologies to the transit bus to enhance transmission efficacy.

• Because the motor coach does not have two driv e axles, unlike the trac tor trailer, it cannot benefit from switching to a single drive axle.

• Because the motor coach spends more time at high speed, the efficiency benefit of using an 8-speed transmission is estimated to be lower.4-73 Table 4-49 summarizes driveline strategies for motor coaches.

Table 4-49. Driveline and transmission strategies for motor coach
Strategy % FC Benefit Capital Cost Appropriate spec-ing 1 to 3% — Aggressive shift logic and early lockup 1 to 2% $100 Reduced AT parasitics and friction reduction 1 to 1.5% $0 to $500

AMT 4 to 8% -$10,000 36 8-speed AT 1.5 to 2% $1,870 to $2,200 (See Table 4-47)

4.5.4 Class 2b Pickups and Vans

The baseline class 2b vehicle is assumed to use a 6-speed automatic transmission. The capital costs and benefits for transmission and driveline strategies in Class 2b pickups and vans were primarily extrapolated from the NHTSA light-duty rulemaking. Benef its were assumed to be the same for Class 2b vehicles as for the NHTSA “large truck” category (GVW of 5,000 lbs). Capital costs are scaled according to engine to rque, as this is a good proxy for transmission sizing. The results are shown in Table 4-50.

Table 4-50. Driveline and transmission strategies for class 2b pickups and vans
Strategy % FC Benefit Capital Cost Aggressive shift logic and lock-up 1.5 to 2.5% $60 6 speed to 8 speed AT 2.7 to 4.1% $500 to $1,650 AMT 5.5 to 9.5% $700 to $1,400

The following options were considered:

• Aggressive Shift Logic (ASL) and transmi ssion lock-up, estimated directly from the NHSTA report.

• Increased transmission gears: NHTSA estimates that the fuel efficiency benefit of increasing from a 4/5 speed AT to a 6/7/8 speed AT ranges from 2.7 to 4.1 percent. Capital costs were estimated by scaling the NHT SA data to the torque of a typical Class 2b engine, as shown in Table 4-47.

36 AMTs are a net cost savings in this app lication, as they would be replaced an AT.4-74 • Automatic-Manual transmission: Capital co sts were estimated by scaling the NHTSA data to the torque of a typical Cla ss 2b engine, as shown in Table 4-47.

4.6 Hybrid Technologies

4.6.1 Overview
Hybrid vehicles represent a major fuel savings oppor tunity, particularly for vehicles that travel on duty cycles with frequent starts and stops or that spend large amount of time idling. Hybrid vehicles can improve the fuel efficiency of medium and heavy-duty vehicles in a number of ways:

• Regenerative braking : Hybrid vehicles can recapture vehicle kinetic energy using electric motors or hydraulic pumps a nd store this energy for later use.

• Engine-off at idle : A hybrid can shut the engine off when the vehicle is stopped. In medium and heavy-duty vehicles, three differe nt types of idle reduction are possible:

– Shutting the engine off at short stops, such as at traffic lights or package drop-off points. This is primarily important on urban pickup & delivery (P&D) routes.

– Electrification of overnight hotel loads, wh ich is primarily beneficial on line-haul vehicles.

– Electrification of power take off (ePTO) sy stems: service trucks such as utility vehicles operate

• Increase engine efficiency : A hybrid system can be used to improve the operating efficiency of the engine (i.e., the “drive cycle efficiency” that was discussed in the Section 4.1). This can be accomplished in several ways:

– Launch assist: The hybrid energy source (eith er electricity, as in a hybrid-electric vehicle, or hydraulic power, as in a hydraulic hybrid) can replace or supplement engine power when the engine is at an unf avorable point on its operating map. This is the logic behind “launch-assist” systems, wh ich use only electric or hydraulic power during low speed, low load operation.

– Down-sizing: The hybrid system can be us ed to supplement engine power at peak load. In theory, the engine can then be down-sized. Down-sizing saves weight and reduces engine pumping losses 37 . In practice, this approach is only viable for vehicles that infrequently operate at high load. Vehicles that sp end a large fraction of time operating at high load will quickly deplete th e energy storage if this energy is being used to supplement the engine at high load.

37 Reduced pumping losses is primarily a benefit for spar k-ignition engines, but of some benefit in diesels.4-75 – Emissions integration: In theory, a hybrid system can be used to supplement engine power and reduce emissions.. This woul d allow engine manufacturers greater flexibility in reducing fuel consumption and emissions. In practice, current heavy duty emissions standards only regulate engi ne-out emissions, so using an innovative hybrid strategy that reduces vehicle emissions does not offer any current regulatory benefit.

• Accessory electrification (HEVs only): Given the availabi lity of electric power, HEVs enable accessory electrification, which allows parasitic loads to be run on an as-needed basis. Electric accessories can also be mo re efficient than belt-driven systems.

• Systems integration : Electrification can enable waste he at recovery. Waste heat recovery systems can generate and store electricity allowi ng waste heat to be used when it is most beneficial to system effici ency. In addition, some engine manufacturers and suppliers suggested that the flexibility offered by hybrids (e.g., down-sized engines, accessories decoupled from the engine) could offer aerodynami c benefits especially in Class 8 over the road trucks.
The benefits of hybridization va ry widely depending on the duty cycle. This dependence is apparent even within a single homogeneous fleet using similar vehicles ov er ostensibly similar duty cycles. For example, data was presented to the committee that showed, for the same fleet, hybrid benefits varied on P&D routes from 10 to 35 percent [Davis 2008, Site Visits]. Similarly, controlled testing showed that similar bus es operating on the stop- and-go CBD duty cycle demonstrated a 50 percent fuel savings, while those operating on a commuter duty cycle offered a 12 percent savings. Given this variance, it is ve ry important to carefully define the duty cycle when assessing the fuel consumption benefits.
Estimates of the fuel consumption benefits of hybrids are based on a loose consensus of published data and information that was furnis hed to the committee. One important point to stress regarding these estimates is that compan ies frequently report the benefits of hybrids in terms of fuel economy (i.e., MPG). As discussed in the introdu ction, fuel efficiency benefits are presented in terms of fuel consumption (gallons per mile). While the difference between the percent fuel economy benefit and the percent fuel consumption benefit are minor for differences on the order of a few percent, the difference gr ows as a function of th e percent benefit. The relationship between the two is as follows:

benefit benefit FE FC % 1 1 1 % + − = Equation 4

In the case of hybrids, for which fuel economy benefits of 30 to 40 percent are frequently reported, the difference between data presented in the technology matr ix and that frequently cited in company literature and presentations to the co mmittee is noticeable. In this case, the fuel consumption benefit would range from 23 to 29 percent.
This chapter first summarizes the various hybrid architectures that ar e either currently in production, or that industry is developing. Then, we discuss factors that will influence the4-76 adoption of hybrid technology. The final portion of this chapter matches architectures that are discussed in this section to th e specific applications that fo rm the focus of this report.
4.6.2 Overview of Hybrid System Architectures
A number of different system arch itectures are being considered fo r the applications of interest. These are summarized in Table 4-51.

Table 4-51. Hybrid architectures

Architecture Technology Status Primary applications Medium Duty/Heavy Duty Parallel HEV Available now: Eaton, Azure, Volvo Refuse, Urban Pickup & Delivery (P&D) Medium Duty/Heavy Duty Parallel HEV w/ePTO Available now: Eaton, Volvo Bucket Truck

Parallel Gasoline or Diesel HEV Bus Available now: ISE, Enova, BAE Transit Bus

Dual Mode Diesel HEV Bus Allison Transit Bus
Series Gasoline or Diesel HEV Bus Available now: ISE Transit Bus

Parallel Hydraulic Hybrid Introduced in 2009: Eaton, Parker Hannifin, Crane Carrier Refuse, Urban P&D

Series Hydraulic Hybrid Demo vehicles Refuse, Urban P&D Parallel Class 2b No production plans Class 2b pickups & vans Dual Mode Class 2b No production plans Class 2b pickups & vans
Line-haul dual-mode HEV Demo vehicles Line-haul Tractor trailer, Line-haul parallel HEV Demo vehicles Line-haul Tractor trailer, motor coach

4.6.2.1 Parallel Hybrid-Electric Vehicles
A parallel HEV couples a small electric motor to the engine crankshaft (in a pre-transmission architecture), or to the drive axle (in a post-transmission architecture). Pre-transmission architectures are more prevalent. In a parallel architecture, the motor and the engine are both directly coupled to the drive shaft; the motor can be used to supplement or replace engine power during engine transients (especially at low sp eeds—so-called “launch assist”), or to recover kinetic energy through regenerative braking. Curr ent systems use both lithium-ion and nickel metal-hydride (NiMH) batteries, as well as u ltra capacitors, although th ere is widespread consensus that eventually lithium-ion batteries will dominate. Energy flows, power conditioning, and battery management are controlled by power electronics and an elec tronic control module. An example of one medium-duty parallel hybrid is shown in Figure 4-18.4-77 Figure 4-18. Parallel hybrid architecture [Coryell 2008]

Parallel HEV systems are currently available in transit bus, motor coach, and Class 3-6 box & bucket trucks, and in fleet demonstration stage for refuse haulers. There have been a few demonstrations of Class 8 tractor trailers using a parallel architecture. We speculate that in the future, they may gain market share for Cla ss 2b pickups and vans, although no systems are currently under development.
4.6.2.2 Series Hybrid-Electric Vehicles
A series HEV couples a small engi ne in series to an electric generator, which connect to an energy storage system and an electric motor. The mo tor is directly coupled to the drive shaft. In a series architecture, the electric system provides all of the motive energy for the vehicle, while the engine maintains energy storage charge level within a specified tolerance. This allows the engine to operates in a high-efficiency regime all of the time, which can offer benefits on highly transient duty cycles. However, because energy fr om the engine is converted to electrical and then mechanical energy, a series architecture in curs losses in the dr iveline that make it undesirable for steady-state, high -speed duty cycles. Series hybrids are used in some transit buses, but not in any other applications.

4.6.2.3 Dual-Mode Hybrid-Electric Vehicle
A dual mode system uses a double clutch system to switch between parallel operation, in which the engine and motor are both coupled to the drive shaft, and series mode, in which the engine is decoupled from the direct drive. A dual-mode vehi cle operates in series mode at low speed, and in parallel mode at high speed. At low speed, the engine operate s only on an as-needed basis, turning on to charge the battery when it is at low state-of-charge. At high speed, the engine switches to a direct dr ive, with the motor recovering brak ing energy and supplying supplemental power as dictated by the vehicle controls.4-78 A dual-mode system has been demonstrated by Arvin Meritor in Class 8 tractor trailer in a single vehicle, but they do not have any firm productio n plans. A dual-mode system has also recently been deployed in large light-duty pickups (e .g., the Cadillac Escalade, Chevy Tahoe, and the GMC Yukon), so we speculate that this archit ecture could be deployed for Class 2b pickups and

vans.
4.6.2.4 Hydraulic Hybrids
Hydraulic hybrid vehicles employ the same ba sic architecture as hybr id-electric vehicles. However, in a hydraulic hybrid vehicle, the batt ery is replaced with a hydraulic accumulator, and electric motor/generators are replaced with hydraulic motors/pumps. As in a hybrid-electric architecture, kinetic energy from braking can be recovered and stored : in a hydraulic hybrid, braking energy is used to drive a hydraulic motor that pumps fl uid from a low pressure fluid reservoir, to a high pressure accumulator. This energy can then be used to supplement engine power by releasing the fluid in the high-pressure accumulator back to the low-pressure reservoir, driving the motor in process (Figure 4-19).

Figure 4-19. Parallel Hydraulic Hybrid (“Launch Assist”) Architecture [Gotting 2007]

In practical terms, the key discriminator betw een a hydraulic hybrid and a hybrid-electric system is that hydraulic systems can recover energy far mo re efficiently, while electric systems can store significantly more energ y. Current hydraulic hybrids are cap able of capturing on the order of 70 percent of kinetic energy from heavy-duty vehicl es – this is due to both the high rates at which power can be recovered and the fact th e energy storage system is virtually lossless [Gotting 2007]. In contrast, a hybrid electric vehi cle is forced to scr ub a significant amount of braking energy using conventional friction brakes , and it must also deal with roundtrip energy losses from electrochemical energy storage syst ems. Conversely, the energy density of hydraulic storage is significantly lower than that of elec trical energy storage. Due to these differences, hydraulic hybrids are targeted for power-driven app lications – that is, duty cycles that have high regenerative braking requirements but relatively low energy requirements, such as refuse trucks and house-to-house delivery.4-79 Parallel hydraulic hybrids are curre ntly available for refuse trucks , but suppliers also intend to introduce hydraulic launch assist systems for ur ban package delivery vehicles and shuttle buses in the next several years [Gotting 2007, Site Visits ]. Series hydraulic hyb rids are still in the prototype stage. They are being evaluated for pic kup & delivery vehicles and for refuse haulers, for which they have demonstrated fuel cons umption reductions on the order of 50 percent [Kargul 2009].
4.6.3 Cross-Cutting Issues and Future Outlook
During discussions with manufact urers and suppliers, a number of overarching themes emerged with respect to hybrid technology. Thes e issues are summarized below:
Capital costs : Due to low production volumes, hybrid systems are currently prohibitively expensive for many applications. Depending on a nnual mileage, payback for urban delivery or refuse vehicles is currently 5 to 10 years (n ot including brake savings). There is general consensus that as production volumes increase, costs will decrease significantly (see Figure 4- 20). This is particularly true for battery technology. Current sy stems use both NiMH and lithiumion batteries; in the bus market, ultra capacitors are also used. NiMH batteries are the lowest cost option (estimated on site visits at $700 to $800/ kWh). Lithium-ion batteries are currently a lowvolume item in the automotive sector. However, as the light-duty hybrids switch to using lithium-ion, these volumes should increase and costs come down significantly.

Figure 4-20. Lithium-ion vs. NiMH cost curves [Miller 2006]

Reliability : In hybrid-electric systems, battery life and performance over the life of the vehicle is still unproven. Manufacturer s currently offer warranties that ra nge from 3 years (standard) to 6 years (extended), and expect systems to last ei ght years [Ham 2008, Site Visits]. Eight years is4-80 a typical service life for a servi ce or delivery vehicle a nd 12 years is the servic e life for a transit bus. However, system reliability over the life of the vehicle has not yet been demonstrated in any large fleet tests. In addition, batteries are freque ntly oversized as a mean s of reducing the depth of discharge and to manage power fade as the system ages. End-of-lif e may be particularly problematic in line-haul applic ations, which may go through several owners and last for upwards of 15 to 20 years.
Similarly, hydraulic hybrids have not been te sted in large numbers over a full automotive lifetime. Components such as hydraulic pumps/m otors have in many cases been developed specifically for hydraulic hybrids, and will need to be thoroughly vetted.

Electrification of accessories . These issues were discussed in greater detail in Section 4.1. It was mentioned during several differe nt site visits that these part s are not currently available in large quantities, leading to high cost. Electrifying accessories will a llow the engine to shut off at idle, which can offer significant (~5 percent) additional fuel savings on urban routes. Some systems are already fully electrifying accesso ries, but adoption is not yet universal.

Brake O&M benefits : In addition to saving fuel, hybridizati on significantly reduces brake costs. Suppliers and OEMs expect that hybrids will more than double the brake life. For some applications, these savings can outweigh the fuel savings.
System integration : As hybrid systems become more fu lly integrated into overall vehicle architecture, there are a nu mber of opportunities to fu rther optimize the system:

• Depending on the application, hybridizing a ve hicle can enable engine down-sizing. Currently, this is not widely done . Part of the reason is that in dustry is still figuring out which applications can use a down-sized engine w ithout sacrificing mission performance. Another important factor is that smaller engines ma y be unavailable that meet medium/heavy-duty warranty requirements. One supplier suggested th at they would be able to offer optimized, right-sized powertrains at volumes of 5,000 to 10,000 vehicles per year.

• There is opportunity for s ubstantial integration between hybrid systems and exhaust aftertreatment systems. For example, a system designer could vary engine load to manage exhaust gas temperature, thereby offering emi ssions benefits. However, current standards measure engine-out emissions. To get credit fo r any benefit, EPA would need to switch to measuring emissions on a vehicle basis or de velop a method to credit the lower vehicle emissions.

• Improved system power density, component effici ency, and design integration is expected to offer additional fuel savings opportunities.

• Electrification is viewed as an enabler for more efficient waste-heat r ecovery systems – such as electric turbo-compounding or electric bot toming cycles. In a hybrid vehicle, electric waste heat systems can offer an additional 1 to 2 percent efficiency benefit at neutral cost compared to an equivalent mechanical waste-heat system.4-81 • By narrowing the design window, hybrid systems enable the engine to be optimized to deliver peak efficiency within a narrow operating band. This oppor tunity applies primarily to dual-mode or series systems.
Taken as a whole, improved systems integrat ion can offer an additional 5 to 10 percent improvement in fuel efficiency in future sy stems. In tandem, higher sales volume can reduce capital costs by a factor of two.
4.6.4 Summary — Hybrid Applications
This section summarizes the hybrid systems that ar e currently available, system costs and fuel consumption benefits, and future outlook for each of the vehicle classes that form the focus of our analysis.
4.6.4.1 Class 3-6 Straight Box
Straight box trucks typically travel on an urban pickup and delivery (P&D) duty cycle that matches very well with hybrid-ele ctric and hydraulic hybrid archit ectures. Over the long-term, there is also potential for plug-in hybrid or all-electric vehicles to come into this market segment.
All of the major OEMs currently offer production HEVs in this segment (see Table 4-52). Eaton’s system is the most common system; they have sold approximately 1,400 units since launching series production. These systems have de monstrated fuel consumption benefits on the order of 20 to 25 percent, although benefits vary considerably depending on the duty cycle. The production systems all use a parallel hybrid arch itecture and either currently use lithium-ion batteries, or intend to in the near future . Current costs range from $35,000 to $42,000 [Site Visits, Merrill 2009, Laviolette 2009]. Based on fee dback offered during site visits, there is general agreement that increased automotive lithium-ion production vo lumes could decrease these costs by a factor of two. There are also a number of opportunities to continue to optimize the system. These include full el ectrification of accessories, whic h will allow engine shut-down at idle; integration of the hybr id system with emissions cont rol; engine down-sizing; and improved integration and packaging. In combin ation, these enhancements could improve fuel consumption benefits by another 5 to 10 percent.

Table 4-52. Production-intent medium duty and heavy duty HEV systems, no ePTO a
System Attribute Eaton Volvo Azure Motor (peak) 44 kW 120 kW 100 kW Battery Li-Ion, 2 kWh Li-Ion NiMH 2.4 kWh; 288 V
% FC 20 to 25% 20% 23 to 25%
No Idle? No Yes Yes
Elec. Launch? Yes Yes – 12 MPH Yes Applications Class 3-7 Delivery; Refuse soon Refuse; Delivery soon Small Delivery, Shuttle4-82 a Site Visits, Carpenter 2008, Ham 2008, Vo lvo 2009c, Volvo 2009d, Azure 2009, GCC 2008 Hydraulic hybrid vehicles (HHVs) have not yet b een commercially intro duced in this segment but are intended as future offering for package delivery vehicles. Both parallel and series HHVs have potential in this segment. The fuel consum ption benefit for the parallel HHV is estimated to range from 20 to 25 percent [Gotting 2007]; base d on feedback from site visits, costs are estimated to range from $30,000 (high volume) to $40,000 (initial production), as shown in Table 4-53. The series HHV has been demonstrated to offer 40 to 50 percent fuel consumption benefit [Kargul 2009]; estimates provided during s ite visits suggest an incremental cost of $40,000 (high volume) to $50,000 (low volume).

Table 4-53. Hybrid technology capital costs and FC benefits for class 3-6 box trucks

Architecture Capital Cost %FC Benefit Intro year Weight Parallel HEV $35-$40K (Low) 20 to 25% 2007 450 lbs Parallel HEV, Future $18-$20K (High) 25 to 35% 2014 350 lbs

Parallel HHV $40K (Low) $30K (High) 20 to 25% 2011 1,000 lbs

Series HHV $50K (Low) $40K (High) 40 to 50% 2013 ~1,500 lbs

For some applications, plug-in hybrid or fully el ectric vehicles could greatly reduce or eliminate fuel use at low cost. However, these syst ems were not fully evaluated for this study.

4.6.4.2 Class 3-6 Bucket Trucks
Bucket trucks typically spend onl y a few hours per day driving, and the rest of the time idling to operate onboard machinery. This extensive id le time presents a major opportunity for hybridization. Most of the HEV systems offered in the straight box truck segment are also offered with electronic power take-off (ePTO) syst ems targeted for service and utility vehicles. These ePTO systems use the same architecture as the conventional HEV, but include a larger battery pack that is capable of powering mission loads for several hours at a time. On a typical duty cycle, the engine is require d to turn on for only short (~6 mi nute) periods to recharge the battery every one to two hours.
HEVs with an ePTO system have demonstrated a 30 to 40 percent reduction in fuel consumption, and nearly 90 percent reduction in idle time. Capital costs estimates for these systems range from $49,000 to $52,000 [Site Visits, Merrill 2009], as shown in Table 4-54, but have the same potential to realize signif icant cost reductions due to battery scale as the straight box segment. In high-volume, these costs could decrease to $25,000 to $30,000. Grid-charged vehicles – either plug-in hybrid or electric vehicles – could even tually become important in this segment.4-83 Table 4-54. Hybrid technology capital cost and FC benefits for class 3-6 bucket trucks

Architecture Capital Cost % FC Benefit Intro year Weight
Parallel HEV w/ePTO $49 to $52K (Low) 30 to 40% 2007 ~650 lbs

Future Parallel HEV w/ePTO $25 to $30K (High) 35 to 45% 2014 ~500 lbs

4.6.4.3 Refuse Haulers
Given the high number of stops and starts in a refuse duty cycle, re fuse trucks are ideally suited to the highly efficient energy recovery capabi lity of hydraulic hybrid architectures. HEVs are also being evaluated in this segment.
Production parallel HHVs are bein g introduced at the end of 2009. Fl eet tests have demonstrated fuel consumption benefits on the order of 20 pe rcent. These systems can also be tuned to maximize acceleration, which increases productivity by allowing a single vehicle to visit more houses per day. Systems tuned to maximize productivity have been shown to increase productivity by 11.5 percent while d ecreasing fuel use by 14 percent for a total fuel savings of 26 percent. HHVs also offer a significant O&M sa vings by more than doubling brake life. Based on information provided during site visits, initi al production systems ar e expected to cost $40,000; with increased volume, costs may come down incrementally. We have estimated a high-volume incremental cost of $30,000.
Parallel HEVs may also gain traction in this segmen t, particularly for smaller refuse vehicles that do not generate as much braking energy. Eaton is considering introdu cing their parallel HEV system in a refuse vehicle, and Volvo has al ready developed such a system. The Volvo/Mack system includes an optional grid-charged compact or system that they claim reduces fuel use by an additional 10 percent; we did not find any info rmation that describes th e size of the battery pack needed to achieve this benefit, but we specul ate that it is much larger than would be viable in a production system [Volvo 2009c, 2009d, GCC 2008] . As such, we have reduced the ePTO benefit by one half. It is estimated that the HEV offers a 20 percent fuel consumption benefit for refuse vehicles at a similar incremental cost to that seen in the box truck segment. The gridcharged compactor option reduces fuel use by 25 per cent, and is estimated to cost the same as the bucket truck ePTO system, as shown in Table 4-55.4-84 Table 4-55. Hybrid technology capital cost and FC benefits for refuse haulers

Architecture Capital Cost % FC Benefit Intro year Weight Parallel HEV $35-$40K (Low) 20% 2010 450 lbs Parallel HEV (Future) $18-$20K (High) 25 to 30% 2014 ~350 lbs Parallel HEV, ePTO $52K 25% 2010 ~650 lbs Parallel HEV, ePTO (Future) $25 to $30K 30 to 35% 2014 ~500 lbs Parallel HHV $40K (Low) $30K (High) 20 to 25% 2009 1,000 lbs

Series HHV $50K (Low) $40K (High) 40 to 50% 2013 ~1,500 lbs

4.6.4.4 Class 8 Tractor trailer
A line-haul duty cycle limits the amount of ener gy that can be recovered from regenerative braking. Rather, the advantages of hybridizi ng in this segment come from electrifying accessories and hotel loads, as well as limited gains from energy recovery and launch assist. Hybridizing a tractor trailer may also act as an enabler for wast e heat recovery or aerodynamic drag reductions. The benefits of a hybrid on a line-haul du ty cycle are expected to be much lower than those seen for urban vehicles; however, given the high annual mileage in line-haul applications, many in industry are optimistic that HEVs will become market viable in the next five years.
Two different hybrid archite ctures are being considered for Cl ass 8 tractor tra ilers: a dual-mode HEV (Arvin Meritor’s system) [Kramer 2008], and a parallel HEV (Eaton’s system) [Coryell 2008, Carpenter 2007]. Over the road benefits (i.e., not including idle reduction) are estimated to range from 5 to 7 percent for the parallel system [NESCCAF 2009, Coryell 2008], and 6 to 9 percent for the dual-mode 38 . The benefits for both architectur es are unproven in real-world applications, and feedback offered on site visits in dicated that the actual real-world benefits are significantly lower. However, the systems that demonstrated these lowe r real-world benefits were not optimized for line-haul operation and did not include a full slate of electric accessories. As such, we have used the estimates from drive cycle modeling, which more fully characterized the hybrid system’s capabilities.
These on-road benefits are supplemented by overn ight hotel road reduction, which reduces fuel use by an additional 5 to 8 percent, similar to that observed for APU idle reduction systems. Hotel loads are met by running the engine for a fe w minutes (4 minutes pe r hour, according to an Eaton/PACCAR demonstration) to recharge the ba ttery [Carpenter 2007]. Both architectures are in the early development stage.

38 Arvin Meritor has claimed benefits of 10 to 15 perc ent, but these estimates include overnight hoteling.4-85 Feedback offered on site visits suggest that demo nstrated on-road fuel consumption benefits of 6 to 7 percent is needed to interest fleets in this application. There is poten tial to further refine these initial prototype systems to narrow the engine’s design window (thereby increasing engine efficiency) and possibly allow further integr ation with the emissions control system. Hybridization of the line-haul segment can also ac t as an enabler for elect ric waste-heat recovery and for improved vehicle aerodynamics (by rem oving belt driven accessories, for example).
Incremental costs for the parallel architectur e are estimated to range from $30,000 to $40,000 for initial production; and come down to $20,000 to $25,000 for high volume production. The dualmode system is estimated to cost $45,000 to $55,000, which could drop to $25,000 to $30,000 in high volume. Costs for the parallel architect ure are based on bottom-up costing from the NESCCAF/ICCT study; these are fa irly consistent with our proj ection for medium-duty hybrids, which we believe will be of similar size. Th e dual-mode system requires additional energy storage (perhaps 10 to 20 kWh in a production syst em, versus ~4 kWh in a parallel architecture), and an additional motor/generator. The higher co st estimate attempts to account for this additional hardware. Table 4-56 summarizes the be nefits and costs for these hybrid systems.

Table 4-56. Hybrid technology capital cost and benefits for class 8 tractor trailer hybrids a

Architecture Capital Cost % FC Benefit Intro year Weight Parallel $35 to $45K (Low); $20 to $25K (High) 5 to 7% 2013 ~500 lbs

Dual-Mode $45 to $55K (Low); $25 to $30K (High) 6 to 9% 2013 ~750 lbs

a Does not include idle reduction benefits

4.6.4.5 Transit Bus
Hybrid powertrains are already wide ly deployed in the transit bus segment, due in large part to large federal subsidies (90 per cent of the incremental costs of hybrid systems are funded). 39 They are estimated to comprise 25 to 30 percent of the market in 2009. Most of the systems on the road use a parallel diesel configuration, although diesel series hybrids and gasoline series hybrids are also offered.

As transit buses are the most matu re market segment, they offer insight as to the impact of duty cycle on the benefits of hybridizat ion. Road testing performed on 40 ft transit buses at Altoona using SAE Type II fuel economy test procedures are summarized in Figure 4-21 for a variety of bus manufacturers [Altoona]. The Altoona tests were performed on three bus test cycles: central business district (CBD), Arterial, and Commuter. The arterial and commu ter cycles are higher speed and have less stops compared the CBD cycl e. The CBD cycle includes acceleration from 0 to 20 mph, followed by a segment of 20 mph steady speed, a deceleration, and idle. This is

39 For hybrid and alternative fueled buses 80% of the diesel/baseline bus is funded and 90% of the incremental costs of the hybri d or alternative bus is also co vered by Federal subsides.4-86 

### Road and Dyno Tests

0 2 4 6 8 10

0 10 20 30 40 50 Cycle Average Speed (mph)Fuel Economy (mpg) New Flyer 2007 diesel

New Flyer 2005 hybrid

New Flyer 2004 gasoline hybrid
Orion 2003 diesel

Orion 2002 hybrid

Orion 2004 hybrid

Gillig 2004 diesel

Gillig 2004 hybrid CBD Arterial Altoona Commuter

50% 18% 12% A

verage HEB Benefit

Figure 4-21. Fuel economy benefits of 40-foot hybrid transit buses compared to 40-foot diesel transit buses

repeated over 2 miles. Data on this figure also includes several dynamometer tests performed on buses over the CBD cycle [Clark]. The New Flyer bus es were tested with the ISE series system (gasoline) and the Allison EV40 system. The Orion buses used the BAE hybrid system. The Gillig buses used the Allison EV40 hybrid system.
These data indicated that over the CBD cycle fu el economy increases some 50 percent compared to the non-hybrid diesel baseline . The benefit decreases to 18 and 12 percent for the arterial and commuter cycles, respectively. This decrease is expected since the hybrid system’s benefit is increased for cycles with more stops and starts (regeneration energy from braking can be used during acceleration).
The curb weight the diesel baseline buses ra nged from 27,000 lbs to 28,000 lbs and the hybrid buses curb weight ranged from 28,000 lbs to 30,000 lbs. The weight of the hybrid systems ranged from a low of 940 lbs to a high of 2,800 lbs. Both New Flyer and Orion indicate that they will be introducing new hybrid buses that will be more streamlined and some 2,000 lbs lighter than those previously tested at Altoona. Their di esel buses will also be lighter--in the range of 25,000 lbs curb weight [New Flyer, Orion]
Based on these data, fuel consumption benefits range from 12 to 50 percent depending on the severity of the duty cycle. Incrementa l system costs are $200,000 to $220,000, depending on4-87 hybrid architecture and whether a gasoline or diesel engine is used. It is unclear to what extent these high costs are a function of low production vol umes (and hence reflect that actual system cost), and to what extent they simply reflect what the market will bear – particularly in light of the heavy government subsidies. These results ar e summarized in Table 4-57. It should be noted the transit bus market is fairly small – on the order of 5,000 buses per year – and hybrids already have 25 percent market share, so production volumes will not increase that much beyond present day levels.

Table 4-57. Hybrid technology capital cost and benefits for transit buses

Architecture Incremental Capital

Cost % FC Benefit Intro year Incremental Weight Gasoline Series $200,000 25 to 35% a Available – ~150 on road 2,000 lbs

Diesel Series $220,000 30 to 40% Available – ~ 75 on road 2,600 lbs
Diesel Parallel & Dual-Mode or dual mode $200,000 22 to 35% b Available – 2,000 to 3,000 on road 940 to 2,840

a Site Visits b FTA 2005, Altoona

4.6.4.6 Motor Coach
Currently, 20 to 25 percent of hybrid bus system s are sold in motor coaches [Site visits]. Presumably, these systems go into motor coaches that travel in primarily urban applications. Longer term, we would expect motor coach hybrid systems to more closely resemble the systems that are being considered for line-haul applications . This is because the motor coach duty cycle is more similar to a regional line-haul tractor trailer than to a transit bus.
The track testing discussed in the transit bus section (see Figure 4-21) indicates that hybrid benefits on a commuter cycle are approximately 12 percent. The Northeast Advanced Vehicle’s Consortium showed on-road fuel savings for an MCI motor coach of 5 to 40 percent on a highspeed suburban duty cycle [FTA 2005]. MCI has quoted fuel savings th at range from 20 to 54 percent for their system [MCI 2008], but we speculate that these numbers correspond to a motor coach operating on a city or suburban drive cycle.
It seems unlikely that hybrids will have a major impact in this sector given the high cost of hybrid bus systems and the relatively low bene fit on a commuter motor coach duty cycle. We have considered two poten tial hybrid architectures fo r the motor coach segment:

• A parallel HEV system similar to that used in transit-buses. This system would have a large (>20 kWh) energy storage system, and is likely oversized for this application.

• Longer term (2015 timeframe), a parallel HEV sy stem similar to that prototyped for Class 8 tractor trailers. This system would likely be better matched to the motor coach duty cycle, but it is not clear that there will be enough inertia to develop such a system for this4-88 market segment. Given the low volume of vehi cles in this segment, we only included the “low volume” cost estimate for the line-haul hybrid.
We anticipate benefits th at range from 7 to 15 percent, and co sts that are similar to the analogous system from either the transit bus or Class 8 line-haul segment (see Table 4-58). We suspect air conditioning loads will be one of the major dr ives for considering hybr ids in the application.

Table 4-58. Hybrid technology capital cost and benefits for motor coaches

Architecture Capital Cost % FC Benefit Intro year Weight

Parallel HEV Transit Bus $180,000 to $220,000 a 10 to 15% Available – a few hundred on the road 1,000 to 2,000 lbs
Parallel HEV

Line-haul $30,000 to $40,000 7 to 10% 2015 500 lbs

a MacPherson 2008

4.6.4.7 Class 2b Pickups & Vans
No hybrids systems are currently offered in the class 2b segment, and we are not aware of any specific plans to begin production. Nor does th e NHTSA [2009] rulemaking for light-duty vehicles anticipate any new “large truck” (5,000 to 6,000 lb GVW) hybrids coming into the market by 2011; as such, they did not explicitly model the costs or benefits of such a system.

We have estimated the costs and benefits for tw o different class 2b hybrid systems: a dual-mode hybrid, similar to those used in some of the larg er light-duty hybrids (for example, the Cadillac Escalade); and a simple integrated starter/generator parallel hybrid similar to the Eaton system or the Azure system used in Class 3-6 vehicles.
System costs were estimated by extrapolating NHTSA’s hybrid vehicle co st model to Class 2b vehicles. The NHTSA cost model includes compone nt cost estimates (expressed in $/kW, for example) and sizes for a mid-size vehicle, and then scales these costs to different vehicle segments according to certain vehicle parameters, such as gross vehicle weight, footprint, and engine displacement. Applying this cost model across a range of Class 2b vehicle weights (6,000 to 10,000 lbs) and engine displacements (5.4L to 6.8L) gives high volume cost estimates as shown in Table 4-59. Because the NHTSA study uses component costs consistent with high production volumes, we have included a low-volum e cost estimate that simply multiplies the high volume cost by a factor of 2.
The fuel consumption benefits for a Class 2b dual- mode hybrid is estimated to range from 20 to 30 percent; this is based on estimates from Vy as [2002] and EPA [2008] – neither of which applies specifically to this market segment. No estimates are available for the benefits of a parallel Class 2b vehicle. Given the mixed duty cycle, we estimate benefits would range from 15 to 20 percent for this vehicle class. The EP A study also includes a 42V start-stop hybrid; however, feedback provided during site visits suggested that the benefits for this configuration are unproven, so we did not include it.4-89 Table 4-59. Hybrid technology capital cost and benefits for class 2b pickups and vans

Item Parallel Dual-Mode
FC Benefit 15 to 20% 20 to 30% High-volume cost (NHTSA cost model) $8,200 - $10,300 $12,000 - $17,000

Low-volume cost (NHTSA x 2) $16,400 - $20,600 $24,000 - $34,000

Intro Year 2014 2014 Weight ~200 lbs ~250 lbs

4.7 Idle Reduction
Idle reduction technologies transfer the work done by the main propulsion engine for powering auxiliary systems (such as air conditioners, heater s, and engine warmers) to other more efficient systems. For refuse haulers, transit buses, box and bucket trucks, and motor coaches, idle reduction technologies target reducing in-use idling in traffic or at work sites using electrification of auxiliaries and engine-off at idle. These idle reduction strategies are discussed in the section on engines (Section 4.1) and hybrid vehicles (4.8 ). This section focuses on options to reduce overnight hotel loads in l ong-haul tractor trailers.
In 2000, it was estimated that, on average, diesel intercity tractor traile rs idle more than 1,800 hours per year when parked overnight consuming more than 838 million gallons of fuel annually [Stodolosky 2000]. However, idling regul ations have been enacted in 25 states to address urban air quality concerns and may have motivated a reduc tion in the annual average idling hours in large part through the introduc tion of anti-idling technologies [A TRI 2009]. As such, our estimates of the average engine idle time, which are based on data that is now nearly ten years old, may be high. On the other hand, a high mileage truck may id le significantly more than this: a truck that idles for eight hours per day for 300 days per year spends 2,400 hours per year in a hotel mode.
EPA estimates that fuel use during idle uses 0.8 to 0.9 gallons of fuel per hour [Smartway]. This equates to 1,440 to 2,160 gallons of fuel per year – or 7 to 10 per cent of the total fuel used by a line-haul truck 40 . Hence, reducing these overnight hotel load s for tractor trailers can significantly impact fuel efficiency in this segment. High dies el prices and anti-idling regulations have led to the development of a variety of truck idle reduction technologies. Truck idle reduction technologies fall into five main categories:

• Automatic Shut-Down/Start-Up Systems

• Battery Powered

• Fuel Operated Heaters

40 Assume: 120,000 miles per year, 6 MPG, 1,800 to 2,400 hours of idle at 0.8 to 0.9 gal/hr4-90 • Auxiliary Power Units or Generator Sets

• Truck Stop Electrification
Each idle reduction technology ta rgets a specific set of opera tional requirements. Benefits depend upon the amount of idling, climate, time of y ear, and types of auxili ary loads. There is not one solution that fits the nor thern (high heating loads) and southern (high cooling loads) climates. There is a great deal information on id le reduction strategies, fuel economy and capital costs on EPA’s Smartway website [Smartway 2009b].
4.7.1 Automatic Shut-Down/Start-Up Systems
Automatic engine idle management systems moni tor cabin and engine te mperature and turn the engine on/off as needed to maintain the desired temperatures. Several engi ne manufacturers offer electronically controlled optimized idling control devices. Higher end integrated systems include thermal storage. More advanced systems run th e engine at higher load to keep the maximize engine efficiency when it is on. Table 4-60 ch aracterizes several such systems. We did not receive information as to the rate of fuel use for this type of system. However, Duleep [2008] estimates that these systems reduce fuel consumption by 3 percent.

Table 4-60. Automatic shut- d own/start-up systems comparison

Feature/Supplier BBW IdleSmart Cummins ICON TM Idle

Control TAS TempA-Start Monitors temperature inside and out 

### 9 9 9
Auto starts engine 

### 9 9 9
Increases engine speed for maximum efficiency 

### 9 9
Monitors system (i.e., oil and cab temperature, battery voltage) 

### 9 9 9

Heats and cools cab 

### 9 9 9

Idles down 

### 9 9
Shuts down engine 

### 9 9 9

Transferable to successive trucks 

### 9 9 9 Weight (lbs) 30 na 14 Retail price $3,750 $1,325 $2,500

4.7.2 Battery-Powered
Battery-powered idle reduction systems incorporat e the use of either the vehicle’s battery or a separate battery pack to power the heating and/or cooling of the cab and powering of on-board appliances. A few systems also offer shore power connections. Each of these systems provides between 8 and 12 hours of runtime. Because of this limited duration, they may not be ideal for applications that require longe r term (weekend) heating or cooling. Table 4-61 compares a4-91Table 4-61. Battery-powered idle reduction systems comparisonFeature/Supplier Autotherm T-2500 Energy Recovery System Bergstrom NITE Dometic Driver Comfort System Glacier Bay ClimaCab Idle Free Systems Reefer Link System Kenworth Clean Power Peterbilt ComfortClass Safer Viesa Sun Power TechnologiesHeats cab999999999Cools cab999999999Powers on-board appliances999Circulates heated coolant from engine toheater coils9Runs off of vehicle battery999Runs off separate battery pack99999999Shorepower connection999Automatic start9at engine off99Automatic shut down999Monitors system (coolant temperature, batteryvoltage)99(cab only)999Run time (hours) na 10 10-1510 (heating)12 (cooling)10(cooling)10 8 8-12Thermal storage cooler99Direct fueled heater999Weight (lbs)5 210 na 520161(not includingbatteries)200 550 126 440Retail price$575 to $710 $3,495$3,500 to $7,500$6,895 $7,995 $1,600 $6,9004-92 variety of systems currently available as iden tified by the U.S. EPA Smartway website [2009b]. As shown, each system offers various features and have a retail cost between $575 and $7,500.

Both Kenworth and Peterbilt have introduced idle reduction systems on their products. The Kenworth system is called Clean Power and operato rs could see as high as 8 percent reduction in fuel consumption. The system, however, depends greatly on the application. Operators with substantial heating requirements c ould see the benefit reduced to 1 to 2 percent. Both systems depend on the current battery capacity. Current systems use lithium-ion batteries and manufacturers are looking at various chemistries for future ge nerations. There is an expectation the passenger car market will drive economi es of scale and lower battery costs. We have assumed that these systems fully displace the engine idle load but need to be recharged frequently from an off-board sour ce to achieve this benefit. 4.7.3 Fuel-Operated Heaters Also known as direct-fired heaters, fuel-operated heaters are available to heat either the cab or engine or both (Table 4-62). These heaters use significantly less fuel than the primary engine by supplying heat from either a combustion flame or a small heat exchanger, thereby, eliminating losses from engine friction or heat loss. In MY 07, there was about 10 perc ent market penetration for direct-fired heater option.

Table 4-62. Fuel-operated heater comparison
Espar Heater System Webasto Product North America Feature/Supplier Automotive Climate Control Cab Engine Cab Engine

Heats cab 

### 9 4 models 2 models

Manual or automatic control Yes Auto Auto Auto Battery-powered fuel fired heaters 

### 9 9 9 9 9
Heats engine 2 models 3 models

Fuel use 1 gal per 24 hours 1 gal per 20 hours 1 gal per 4-6 hours 1 gal per 20 hours 0.03 to 0.24 gal per hour

Retail price $920 to $1,200 $1,000-$3,000 $1,000-$3,000

4.7.4 Auxiliary Power Units Auxiliary power units (APUs) provide electricity and heat with the help of a small internal combustion engine equipped with a generator and heat recovery device. Cooling can be provided with the installation of an elec tric air-conditioner in the cab. Ma ny APU devices are available. In addition to those APUs compared in Table 4- 63, Navistar recently announced in a press release 41 :

41 http://www.reuters.com/article/pressRelease/idUS213209+07-May-2008+BW200805074-93Table 4-63. Available auxiliary power unit comparisonSupplierHeats cabCools cabHeats engineFC (gal/hour)110V ACAuto-onShorepowerCapital CostAuxiliary PowerDynamicsYes Yes Yes 0.25 Yes YesBlack Rock Systems 26,000 btu 26000 btu 0.20 or 0.30$7,499 to $8,100Carrier Transicold Yes Yes Yes 0.2 Yes Yes YesComfort Master 31,000 btu 31,000 btu 0.25 Yes Yes Yes$7,200 to $8,100Crawfurd Manufacturing 22,000 btu 22,000 btuDiamond PowerSystems14,500 btu 14,500 btu 0.26 Yes Yes Yes$6,500Double Eagle Industries Yes Yes Yes 0.3 DC$7,000 to $9,000Flying J Yes Yes Yes Yes Yes Yes$6,999Frigette Truck ClimateSystemYes Yes Yes$6,000 to $7,500Idlebuster Yes Yes Yes Yes Yes Yes$6,900 to $7,750Kohler 10,000 btu 12,000 btu Yes YesKool-Gen Optional Yes Yes$6,925Mechron PowerSystems5,000 to10,000 btu10,000 to14,000 btu0.21 YesPony Pack Yes Yes Yes 0.2 DC$7,500Rig Master Power Yes Yes Yes 0.2 Yes$6,300Star Class$5,995 to $6,500Thermo King 13,000 btu Yes Yes 0.04 to 0.14 Yes Yes$8,000 to $10,000(+$3,000 DPF forCalifornia)TRIDAKO EnergySystems30,000 btu 24,000 btu Yes 0.4$8,499Truck Gen Yes Yes 0.2 Yes Yes$6,000 to $7,0004-94 Operating at 4.2 kW, the MaxxPower APU equates to best-in-class fuel consumption of 0.18 gallons per hour. It features EPA Tier IV certification and is in the process of acquiring CARB '08 emissions compliance. Seve ral states currently offer incentives for trucks with idle reduction systems. Pr oduction is slated for later this year.
Note that APUs need to be emissions complia nt to operate in California, which can be accomplished with the installation of a $3,000 DPF [Site Visits].

4.7.5 Truck Stop Electrification
There are currently 138 truck stops equipped with truck stop electrificatio n identified in the Alternative Fuel Data Center (AFDC) Truck Stop Electrification (TSE) database. 42 Located in 34 states, these sites provide truckers the opportunity to “plug-in” to power heaters, air conditioners, lights, and other accessories. Th ere are generally two types of electrified parking spaces: dual system, and single system. A dual system requi res equipment on both the truck and the ground. A single system only requires equipment at the truck stop. Table 4-64 summarizes the various truck stop electrification strategies.

Table 4-64. Truck stop electrification comparison
Supplier Capital Cost Service Fee Dual Systems Phillips and Temro $125 Shurepower $200 to $2,000 $0.50 per hour Teleflex (Proheat) $2,500

Xantrex $1,500 inverter/charger $1,500 electric HVAC $2,500 per space
Single Systems Cabaire Craufurd Manufacturing $8,550 per space IdleAire Technologies $10 adapter $2.18 per hour retail $1.85 per hour fleet

4.7.6 Idle Reduction System Comparison
Idle reduction systems differ in a number of respect s. Some of the key discriminators are fuel use per time; functionality (heating ability, cooling ability, and elec tric loads); infrastructure requirements; and capital Cost. These features are summarized in Table 4-65 for each of the five idle reduction strategies we ha ve examined. Cells that are shaded light green correspond to favorable attributes; cells that are shaded yellow correspond to mild drawback s; and cells that are shaded dark orange correspond to major drawbacks.

42 http://www.afdc.energy.gov/afdc/progs/tse_listings.php4-95 Table 4-65. Idle reduction systems comparisonHeatingCoolingElectricRequiresRechargeInfrastructureService FeeEmissionsControlNeeded?Idle timeavoided peryearFuel Use(gal/hr)% FC BenefitCapital Cost

Engine Ctrl Yes Yes Yes No No No 1,500 to 2,400 ~0.5 3% $1,000 to $4,000

Heater Yes No No No No No 500 to 800 0.2 to 0.3 1.3 to 2.3% $1,000 to $3,000

APU Yes Yes Yes No No In CA 1,500 to 2,400 0.2 to 0.3 4 to 7% $6,000 to $8,000 43

Battery Yes Yes Some Yes No No 1,500 to 2,400 - 5 to 9% $3,000 to $8,000

Shore Power Yes Yes Yes Yes Yes Yes 1,500 to 2,400 - 5 to 9% ~$100

The fuel savings benefits are estimated using the following assumptions, which rely on estimates from the online Smartway fuel savings cal culator [Smartway 2009b], as well as work by Argonne National Laboratory on tr uck idling [Stodolsky 2000]:

• An idling engine consumes 0.8 gallons of fu el per hour. This is based on a Smartway estimate for idle engine fuel consumption, and is consistent with a 4 kW accessory load with an engine operating at 15 percent efficiency. The 21 st Century Truck Partnership estimates a typical accessory load of 3 to 5 kW for a line-haul truck [D OE 2000]. It is possible that current engines have lower idle fuel consump tion rates, but we have no specific data to support this.

• A line-haul truck is assumed to operate under hotel loads for be tween 1,500 and 2,400 hours per year. This range is meant to bracket the range between a medium and high-mileage vehicle.

• A line-haul truck is assumed to use 20,000 gallons of fuel per year on road.

• We have assumed that a direct -fire heater is in-use for 600 to 800 hours per year. Smartway estimates 800 hours per year of heater fuel use.

43 May require a DPF, at an additional cost of $3,0004-96 4.8 Driver Management and Coaching

4.8.1 Overview
Many of the lowest cost, most robust approach es to improve fuel e fficiency revolve around driver management and coaching. These strategi es aim to optimize shift strategies, manage vehicle speed and acceleration, and use telematic systems to optimize route. Significant fuel efficiency benefits may be achieved either te chnologically, or with improved driver training. There is general consensus in industry that driv er variability can lead to a 20 to 35 percent variation in fuel economy (F igure 4-22) [Ang-Olson 2002, Cumm ins 2007, Site Visits]. While none of the technological approaches do as well as the best, most well-trained drivers, technological aids can shift av erage and below-average drivers towards the top performers.

Figure 4-22. Variance in driver performance [Cummins 2007]

Technological approaches to driver management and coaching include telematic systems that help monitor vehicle route; intelligent cruise co ntrol; driver fuel efficiency feedback systems; engine speed and load management controls; and speed governors. Thes e strategies may be employed in tandem with driver training to significantly reduce fuel consumption. Driver management and coaching mechanisms are directed primarily towards Class 8 line-haul tractor trailers. We did not consider th ese technological approaches to dr iver management as a viable strategy in other vehicle classes in the next five to ten years.
At their core, many of the driver management strategies aim to insu re that the engine operates in a high efficiency regime more of the time. This is a different way of achieving the same goal as many of the transmission and driv eline strategies. For example, a fleet can improve a driver’s average cycle efficiency by purchasing an auto matic-manual transmission (AMT); by training the driver in appropriate shift techniques; or by using technology that offers driver feedback and4-97 actively manages vehicle operation. Different fleets have opted to pursue different strategies. For example, one fleet has tested both automatic transmissions and AMTs, but found that they could approach these benefits through driver training, optimi zed shift strategies, speed governors, and smart cruise control.
4.8.2 Description of Management and Coaching Strategies
The following sections will give an overview of dr iver management strategies, and finish with a summary of the total potential for driver management strategies:
Driver feedback/incentives and Training: Driver feedback gauges and fuel efficiency rewards offer a complementary approach to encourage mo re fuel efficient driving. These range from instantaneous fuel economy indi cators to regulated governors that allow drivers to earn higher speed driving if they meet fuel efficiency targets. In addition, fleets diligently monitor the fuel use of their drivers, and can us e this information to reward hi gh-performing drivers or train poor performers. This information can help to decreas e on-road fuel consumption, as well as reduce idle time. Southeastern Freight presented data th at showed that idle time monitoring had reduced idle time by 45 percent in the last year [Drinkard 2009]. Some level of driver feedback monitor is standard on present-day tractors, but units with more f eatures (such as engi ne boost indicator or instantaneous and trip fuel use) include an up charge [Kenworth 2008]. Data gathered by the FMSCA 2009 evaluates several such systems – Detroit Diesel’s ProDriver, Caterpillar’s Messenger, and the Cummins Road Relay 4. They es timate the cost of the Cummins system at $800. A fully integrated driver management system would also include GPS, which is estimated to range in cost from $400 to $800, plus $20 to $40 per month in se rvice fees [FMSCA 2009, www.trackyourtruck.com 2009]. A comb ination of a low-level activity monitor and driver training was estimated by Duleep [2008] to cost $1,400. Although the benefit for individual drivers will vary considerably, an integrated driver training program is estimated in the literature to improve fuel efficiency by 3.8 to 4 percent [Duleep 2008, Ang-Olson 2002].

Based on this cost information, we have character ized several different dr iver feedback/training approaches:
1.) Simple driver feedback monitor: st andard equipment, 1 percent savings
2.) Advanced driver feedback: $800, 1 to 2 percent fuel savings
3.) Advanced driver feedback with GPS system: $1,200 to $1,600, 3 to 4 percent fuel savings
4.) Driver feedback monitors with training programs: $1,400, 3 to 4 percent fuel savings
In combination, we estimate fuel savings that range from 1 to 4 percent, at costs that range from $0 to $1,600.

Route management: Telematic systems using GPS can be used to manage driver routes to avoid bad weather and congestion. These systems can be im plemented at low marginal cost on vehicles that are already GPS-equipped. We estimate that a GPS system costs between $400 and $800,4-98 plus service fees that range from $20 to $40 per month [FMSCA 2009, www.trackyourtruck.com 2009]. We estimate fuel savings potential of up to 1 percent.
Engine and Driveline Management Strategies: These strategies maximize engine efficiency by controlling engine speed 44 and torque characteristics when at cruise speeds. Examples include load-based speed control (offered by Cummins), and multi-torque engines (offered by Detroit Diesel). Load-based speed control limits the engi ne speed available to the driver based on the actual load; this compels the driv er to aggressively up-shift, th ereby saving fuel. A multi-torque engine enables two different tor que settings in high gear, and ma tches the torque to the load – thereby limiting engine speed. Cummins [2007] ha s published real-world data that suggests optimizing shift strategies offers 3 to 4 percent improvement; load-based speed control will not capture all of these benefits. We estimate that it could offer a 1 to 2 percent improvement, which is similar to estimates for the fuel efficiency benefit of multi-torque engines. These options are offered as part of standard packages on 2010 engine s, so we consider them to be cost-neutral.
Speed governors: Speed governors are standard on all Cla ss 8 tractor traile rs, but purchasers have flexibility as to what speed to use. So me fleets and many independent operators do not govern speeds at all. Data was presented to the committee by a numbe r of fleets [Miller 2009, Site Visits] that have opted to govern their speed, and have chosen to do so more aggressively in recent years:

• Con Way Freight went from 65 to 62 MPH

• Con Way Truckload went from 70 to 65 MPH (2.8 percent MPG improvement)

• Wal-Mart currently governs at 65 MPH, but is strongly considering going to lower speed.
Issues with governing speed include potential productivity loss (due to slower freight movement), and resistance from drivers, who ar e paid by the mile. Based on feedback on site visits, none of the OEMs had a firm handle on ho w large the productivity loss is from reducing speed, but there was general consensus that an elasticity of well less than 1 is likely 45 . Given that fleets have been moving towards lower speed oper ation, one would speculate that the benefits outweigh the productivity loss. It should also be noted that to achieve these fuel efficiency benefits, the vehicle drivetrain needs to be matched to the ap propriate speed. One option that guarantees vehicles will be a ppropriately specified and insures speed limit reductions is to hardwire the governed speed at the factory.

Several sources site a rule of thumb that re ducing speed increases fuel economy by 0.1 MPG [Kenworth 2008, Cummins 2007, Ang-Olson 2002]. This corresponds to an elasticity of approximately 1.4 percent fuel savings per mile per hour of speed reduction 46 . However, SwRI modeling for NESCCAF/ICCT [2009] projects an elasticity of 0.4 to 0.5 percent per MPH. Realworld data from Con Way [2009] supports this estimate; they have found that reducing speed

44 Engine speed control is not to be confus ed with vehicle speed governors. The former keeps engine RPM below a specified target; the latter keeps vehicle speed below a specified target.

45 An elasticity of 1 would mean that a 1 percent decrease in s peed leads to a 1 percent decrease in productivity. In general, pe ople felt that a 1 percent decrease in speed might lead to a lower productivity hit – perhaps a 0.2 percent drop.

46 Assumes that going from 70 MPH to 60 MPH in creases fuel economy from 6 MPG to 7 MPG4-99 from 70 to 65 MPH reduces fuel use by 2.8 percent, or 0.56 percent per MPH. We have used the SwRI estimate of 0.4 to 0.5 percen t per MPH in the technology matr ix. This does not include any estimate of potential productivity impacts. Sp eed governors are included as a standard option with current vehicles, so this t echnology is considered cost-neutral.

One factor that could influence th e variation in the literature is that the fuel consumption of a more aerodynamic truck is less sensitive to high- speed driving. Conversely, it is important to recognize that, if road speeds are reduced, aerodynamic drag re duction saves less fuel than it would at higher speed.

Advanced cruise control: Advanced cruise control syst ems include currently available “adaptive” systems, as well as future “predictive” systems. Adaptive cruise control improves fuel economy by adjusting vehicle speed according to surrounding traffic. This helps prevent sudden braking. Predictive cruise contro l will actually be able to ad just vehicle operation based on factors such as traffic and topology. For exampl e, a predictive system could decrease vehicle speed in anticipation of a curve, adjust speed to take advantage of vehicle inertia in hilly terrain, or delay turning on the engine cooling fan just before the top of a hill.
Adaptive cruise control systems are currently availa ble on current vehicles (primarily as a safety feature), but are not widely adopt ed. We did not find any firm es timates of the fuel consumption reduction benefits of adaptive cruise control; we estimate that these systems reduce fuel consumption by less than 1 percent, depending on the driver and drive cycle. According to published cost information, adaptive systems are estimated to range in cost from $1,100 to $3,000; systems for heavy-duty vehicl e vehicles tend to lie at the upper end of this cost range (i.e., $2,000 to $3,000) [JD Power 2009, RITA 2007, Howard 2009].
Predictive cruise control systems rely primarily on telematic information from GPS, as well as computer hardware and software upgrades to ac tively manage vehicle operation to reduce fuel use and improve safety. These systems are just coming to market. For the high-speed long-haul duty cycle on which our analysis focuses, discussi ons during site visits su ggested that predictive cruise control can reduce fuel consumption by 1 to 2 percent [Site Visits]. However, it should be noted that the benefits of predictive cruise co ntrol may be much higher on regional duty cycles that include significant travel on congested roads with a number of stops and starts. We assume that GPS units will already be adopted for ot her driver management or fleet optimization strategies, and that the radar is already included in adaptive systems. As such, we estimate these system costs at $100 – similar to the firmwa re upgrades required for onboard diagnostics.
4.8.3 Summary
Approaches to managing and training drivers ar e summarized in Table 4-66. We have estimated the adoption rate for driver management systems th at are currently availabl e at 25 to 50 percent. Although some features – such as speed governors – are standard on all vehicles, not all users take advantage of them. Our estimate is based on data offered during site visits that suggested that about half of vehicle purchas ers also purchased driver feedb ack information. Given that this is an entry-level type of system, we speculate that adoption rates for more advanced approaches are lower.4-100 Table 4-66. Driver management and coaching strategies –capital costs and benefits
Strategy % FC Improvement Capital Cost Adoption/Intro Yr Training and Feedback 1 to 4% $0 to $1,600 25 to 50% Engine and Driveline Mgmt 1 to 2% - 100% Route Management 0 to 1% $400 to $800 2010 Govern speed 0.4 to 0.5% per MPH - 25 to 50% Adaptive Cruise Cont rol 0 to 1% - 100% Predictive Cruise Control 1 to 2% $100 2012

These approaches to driver management and coach ing that were characterized fall into one of four categories: optimizing shift strategies, limiting road speed, optim izing acceleration and braking, and optimizing the route (Table 4-67). Given that different approaches are used to attack the same problem, it is important to recognize that the benefits of these management and coaching strategies are not additive. As they ar e packaged together, they will offer diminishing returns.

Table 4-67. Driver management and coaching strategies – approach

Strategy Optimize Shift Strategy Limit road speed Optimize Acceleration and Braking Optimize Route

Training and Feedback X X X Engine and Driveline Mgmt X Route Management X Speed Governor X
Cruise Control X

An integrated driver management and coachi ng strategy might include the following elements:

• Speed governed to 60 to 62 MPH

• Onboard GPS

• Some type of driver sweet spot indicator

• Driver training and/or fuel efficiency incentive program

• Advanced predictive cruise control

• Some sort of speed limited engine
In combination, these strategies could reduce fuel consumption by 7 to 8 percent for an average driver.5-1 5. Packages

There has been much discussion in the previ ous sections regarding the importance of not attempting to simply add the benefits of each of the identified fuel savings technologies, in large part because many of the technol ogies will interact and may incr ease or decrease the combined effect. Nevertheless in this sec tion, we will look at specific app lications, assume a specific set of vehicular and operational character istics, and likely fuel savings technologies to identify the capital costs, benefits and payback required for implementation. We fully realize that vehicle modeling is necessary to estimate the combined e ffects of individual techno logies. As such, the results presented here should be view ed as very preliminary estimates.
5.1 Capital Costs, Benefits, and Capital Cost Per Percent Reduction (CCPPR)
Using the results from the analysis of indi vidual technology strategi es, technologies were packaged together to estimate total feasible fuel savings costs and benefits for each vehicle segment. The following tables show the resu lts of this analysis for 2015-2020 technologies. Each of these tables shows the category of fu el savings technologies , a description of the technology, percent fuel consumpti on (FC) benefit, estimated cost s in 2009 dollars (retail price to consumer), CCPPR ($/percent FC improvement), and weight of technology. For each vehicle class, the fuel consumption benefit of the combined technology packages is calculated as follows:

% FC Package = 1 - (1-% FC Tech 1 )(1-% FC Tech 2 )(1-% FC Tech N ) Equation 5
Where % FC Tech x is the percent benefit of an individua l technology. Note that this gives the same result as calculating the ra tio of total fuel used by the package of technologies (FC Package ) to the fuel used with no technologies included (FC Original )

% FC Package = 1 - FC Package /FC Original Equation 6
The tractor trailer results are shown in Table 5- 1. Recall this is a line- haul or over-the-road trucking application accumulati ng over 100,000 miles per year and with a duty cycle dominated by high speed interstate driving. Technologies include advance tractor and trailer aerodynamics, a diesel engine with bottoming cycle approaching 53 percent brake thermal efficiency, wide base single, low rolling resistance tire s, an AMT with reduced driveline friction, tractor hybrid system 47 , driver management, idle reduction, and some light weighting. These technologies provide a 48.9 percent reduction in fuel use at an estimated cost of $84,600. Total vehicle weight is estimated to decline by 470 lbs.

47 Hybrid system could also be added to trailer but this was not consider in this analysis.5-2 Table 5-1. Tractor Trailer 2015-2020 Technology Package

Category Description % FC Benefit Capital Cost CCPPR ($/%) Weight (lbs) Aero Improved Smartway Tractor + 3 Aero Trailers 11.5 $ 12,000 $ 1,043 750

Engine Adv. 11-15L Diesel w/Bottoming Cycle 20 $ 23,000 $ 1,150 800

Tire Improved WBS on Tractor + 3 Trailers 11 $ 3,600 $ 327 -400

Transmission & Driveline AMT, Reduced driveline friction 7 $ 5,800 $ 829 80

Hybrid Mild parallel hybrid w/idle reduction 10 $ 25,000 $ 2,500 400

Mgmt & Coaching 60 MPH Spd limit; predictive cruise control w/telematics; Driver Training 6 $ 1,700 $ 283 —

Idle Reduction Incl. w/Hybrid system — $ — $ — — Tot. Added Weight Added Components -1 $ — $ — +2,030 Weight Reduction Mat. Substitution - 2,500 lbs 1.25 $ 13,500 $ 10,800 -2,500 Total 2015-2020 Package 50.5% $ 84,600 $ 1,674 -470

Two estimates were made for the Class 3-6 appl ications: box truck and bucket truck. This distinction was made to account fo r the differences in duty cycles. The box truck’s application is primarily pickup and delivery, whereas the bucke t truck has extended idle and power take off (PTO) operation. Both of these duty cycles can benefit from hybridization. Table 5-2 shows our estimates for a box truck, and Table 5-3 shows our results for a bucket truck. For the box truck we have included aerodynamic cab and box, our 2015-2020 6-9L diesel engine package (similar to the larger bore engines but without bottoming cy cle), low rolling resistance tires, an 8-speed automatic transmission couple to a parallel hybri d system, and some light weighting. This package results in fuel savings of 47.1 percent at a cost of $43,120 and a net weight increase of 100 lbs.
The bucket truck is similar to the box truck excep t that we have not included any aerodynamics since a lot of time for this application is spent at idle using the PTO. We also made some adjustments of the benefits of the advance dies el engine and low rolling resistance tires based on the differences in duty cycles. The hybrid syst em benefits also increa se due to extended PTO operation. The package results in estimate fuel savings of 49.6 percent at a cost of $49,900 and a net weight increase of 50 lbs.5-3 Table 5-2. Class 3-6 Box 2015-2020 Technology Package

Category Description % FC Benefit Capital Cost CCPPR ($/%) Weight (lbs)
Aero Aero cab, skirts, round corners 6% $ 3,250 $ 542 300

Engine Adv. 6-9L Engine 14% $ 13,000 $ 929 400 Tire Improved LRR Duals 3% $ 300 $ 100 —
Transmission & Driveline 8-Spd AT, Reduced driveline friction, Agg. Shift Logic 4% $ 1,800 $ 450 —

Hybrid Parallel hybrid 30% $ 20,000 $ 667 400 Mgmt & Coaching — — $ — $ — — Idle Reduction — — $ — $ — —
Tot. Added Weight Added Components -4.4% $ — $ — +1,100

Weight Reduction Mat. Substitution - 1,000 lbs 4% $ 4,770 $ 1,193 -1,000

Total 2015-2020 Package 47.1% $ 43,120 $ 915 +100

Table 5-3. Class 3-6 Bucket 2015-2020 Technology Package

Category Description % Benefit Capital Cost CCPPR ($/%) Weight (lbs) Aero — — $ — $ — — Engine Adv. 6-9L Engine 11.2% $ 13,000 $ 1,161 400 Tire Improved LRR Duals 2.4% $ 300 $ 125 —
Transmission & Driveline Reduced driveline friction 3.2% $ 1,800 $ 450 —

Hybrid Parallel hybrid w/ePTO 40.0% $ 30,000 $ 667 650

Mgmt & Coaching — — $ — $ — —

Idle Reduction — — $ — $ — —
Tot. Added Weight Added Components -3.4% $ — $ — +1,050

Weight Reduction Mat. Substitution - 1,000 lbs 3.2% $ 4,770 $ 1,193 -1,000
Total 2015-2020 Package 49.6% $ 49,870 $ 1,005 +505-4 The Class 8 refuse truck results are shown in Table 5-4. Refuse trucks’ duty cycle includes many 100-150 ft stops, compaction, and some high speed operation. The duty cycle is dominant by the many stops and subsequent accelerations. This type of operation is ideal for hybrid drivetrains and we assumed a hydraulic hybrid syst em (a hybrid electric system could also have been assumed). Conservatively, we have assume d 25 percent fuel consumption benefit for the hybrid system. We also included in this pack age an advanced 11-15 L diesel engine without bottoming cycle, improved low rolling resistance tires, reduced driveline friction, and some light weighting. This package results in fuel savi ngs of 38.4 percent at a cost of $50,800 and a net weight increase of 1,000 lbs.
Table 5-4. Class 8 Refuse Hauler 2015-2020 Technology Package

Category Description % Benefit Capital Cost CCPPR ($/%) Weight (lbs) Aero — — $ — $ — — Engine Adv. 11-15L Engine 14% $ 14,800 $ 1,057 500 Tire Improved LRR Duals 2.50% $ 300 $ 120 —
Transmission & Driveline Reduced driveline friction 4% $ 2,700 $ 675 —
Hybrid Parallel hydraulic hybrid 25% $ 30,000 $ 1,200 1,000 Mgmt & Coaching — — $ — $ — —

Idle Reduction — — $ — $ — —
Tot. Added Weight Added Components -3% $ — $ — +1,500

Weight Reduction Mat. Substitution - 500 lbs 1% $ 3,000 $ 3,000 -500
Total 2015-2020 Package 38.4% $ 50,800 $ 1,323 +1,000

The transit bus results are shown in Table 5-5. Due to the stop and go nature of transit buses’ duty cycle, we again included hybridization, as we ll as an advanced diesel engine, improved low rowing resistance tires, improved dr iveline friction, and fairly aggr essive light weighting. This package results in fuel savings of 47.6 percent at a cost of $250,400 and a net weight decrease of 500 lbs. The high costs are primarily due to the high cost of hybrid systems for transit buses. The cost of buses are subsidized by the Federal government and, if we include this subsidy at 90 percent of the incremental costs, then the total package costs is reduced to $54,400, more in line with the costs of Class 3-6 hybrid packages.
Motor coach results are shown in Table 5-6. He re, since these vehicles spend a good portion of their time on interstates we ha ve included improve aerodynamics, an advanced 11-15 L diesel engine with bottoming cycle, low rolling resist ance tires, 8 speed automatic transmission, and minor light weighting. This pack age results in fuel savings of 32 percent at a capital cost of $36,350 and a reduction in vehi cle weight or 400 lbs.5-5 Table 5-5. Transit Buses 2015-2020 Technology Package

Category Description % Benefit Capital Cost CCPPR ($/%) Weight (lbs) Aero — — $ — $ — — Engine Adv. 6-9L Engine 14% $ 13,000 $ 929 500 Tire Improved LRR Duals 1.50% $ 300 $ 200 —
Transmission & Driveline 8-Spd AT, Reduced driveline friction, Agg. Shift Logic 4% $ 1,800 $ 450 —

Hybrid Diesel Series Hybrid 35% $ 22,000 1 $ 220,000 $ 6,286 1,500

Mgmt & Coaching — — $ — $ — — Idle Reduction — — $ — $ — —
Tot. Added Weight Added Components -5% $ — $ — +2,000

Weight Reduction Mat. Substitution - 2,500 lb s 6.25% $ 15,300 $ 2,448 -2,500 Total 2015-2020 Package 47.8% $ 52,400 1 $ 250,400 $ 1,096 $ 5,238 -500

Table 5-6. Motor Coaches 2015-2020 Technology Package

Category Description % Benefit Capital Cost CCPPR ($/%) Weight (lbs) Aero — 8% $ 4,500 $ 563 300

Engine Adv. 11-15L Engine w/Bottoming Cycle 20% $ 23,000 $ 1,150 800

Tire Improved LRR Duals + WBS 3% $ 450 $ 150 —

Transmission & Driveline 8-Spd AT, Reduced driveline friction, Agg. Shift Logic 4.50% $ 2,400 $ 533 —

Hybrid — — $ — $ — — Mgmt & Coaching — — $ — $ — —

Idle Reduction — — $ — $ — —
Tot. Added Weight Added Components -0.75% $ — $ — +1,100

Weight Reduction Mat Substitution - 1,500 lbs 1.05% $ 6,000 $ 5,714 -1,500
Total 2015-2020 Package 32.0% $ 36,350 $ 1,136 -4005-6 The final package we evaluated was for Class 2b pi ckups and vans. The resu lts of this analysis are shown in Table 5-7. For this package we assumed some aerodynamic improvements, low rolling resistance tires, 8-speed transmission coupl ed to a parallel hybrid system and minor light weighting. We assumed that th e baseline engine for this segment was gasoline and our package includes an advanced turbocharge d, downsized stoichiometric dire ct injected gasoline engine. Similar fuel consumption benefits can be achie ved with an advanced diesel engine. This package results in fuel savings of 44.5 percent at a capital cost of $14,710 and at no increase in vehicle weight.
Table 5-7. Class 2b Pickups and Vans 2015-2020 Technology Package

Category Description % Benefit Capital Cost CCPPR ($/%) Weight (lbs) Aero — 3% $ 100 $ 33 —

Engine 5-8L Turbocharged Downsized s-GDI Gasoline Engine 23% $ 4,000 $ 174 —

Tire Improved LRR 2% $ 10 $ 5 —

Transmission & Driveline 8-Spd AT, Reduced driveline friction, Agg. Shift Logic 7.50% $ 1,000 $ 133 —

Hybrid Parallel Hybrid 18% $ 9,000 $ 500 300 Mgmt & Coaching — — $ — $ — —

Idle Reduction — — $ — $ — —
Tot. Added Weight Added Components -0.75% $ — $ — +300

Weight Reduction 3% -- approx. 300 lbs 0.75% $ 600 $ 800 -300
Total 2015-2020 Package 44.5% $ 14,710 $ 331 0

A similar analysis was performed for the interm ediate years 2013 to 2015. These results are not shown in the same format as the previous an alysis for 2015-2020 vehicle segments. Instead we have summarized the results as s hown in Table 5-8 for all the applications: tractor trailer (TT), Class 3-6 box (box), Class 3-6 bucket (bucket), Cl ass 8 refuse (refuse), transit buses (Bus), Motor Coaches (Coach), and Class 2b pickups and vans (2b) This table shows for each application and for each technology package the technology costs, FC benefits, and the CCPPR for technologies that will be market viable 48 between 2013 and 2015. The technologies that are included vary by market segment, but broadly sp eaking, they include a hi gh-cost first generation hybrid system for urban vehicles; and aerodynami c improvements coupled with first generation

48 “Market viable” means that the technology will have matured to the point at which it could be widely deployed; it does not im ply that a particular technology offers attributes (such as rapid payback) that will lead to market adoption.5-7 waste heat recovery on highway vehicles. All of the technologies include significant engine efficiency improvements as indicated.
Table 5-8. Fuel consumption reduction, capital cost, and CCPPR - 2013 to 2015 vehicle technology
Technology TT Box Bucket c Refuse Bus Coach 2b Fuel Consumption Reduction
Aero 5.5%

— — — — — 3.0% Engine 10.5% 9.0% 7.2% 10.5% 9.0% 10.5% 14.0% Weight 0.8% 2.0% 1.6%

— 3.0% 0.7% 0.4% Tire 4.5% 1.8% 1.4% 1.5% 1.0% 1.8% 1.0% Transmission 5.0% 1.5% 1.2% 1.5% 1.5% 2.0% 4.5% Hybrid

— 22.0% 35.0% 20.0% 30.0%

— — Mgmt 3.0%

— — — — — — Idle Reduction 6.0%

— — — — — — Subtotal a 30.6% 32.7% 42.2% 30.5% 39.7% 14.5% 21.4% Added Wt (lb) b 1,530 800 1,050 1,500 2,000 800 0 Adj. FC Total 30.0% 30.5% 40. 2% 28.4% 36.6% 14.0% 21.4% Capital Cost Aero $ 9,000 $ - $ - $ - $ - $ - $ 100 Engine $ 14,200 $ 10,300 $ 10,300 $ 12,300 $ 10,300 $ 14,200 $ 3,000 Weight $ 6,000 $ 1,590 $ 1,590 $ - $ 4,800 $ 3,000 $ 225 Tire $ 900 $ 300 $ 300 $ 300 $ 300 $ 240 $ 10 Transmission $ 5,200 $ 200 $ 200 $ 200 $ 200 $ 300 $ 1,100 Hybrid $ — $ 38,000 $ 50,000 $ 40,000 $ 200,000 $ — $ — Mgmt $ 1,000 $ — $ — $ — $ — $ — $ — Idle Reduction $ 8,000 $ — $ — $ — $ — $ — $ — Total $ 44,300 $ 50,390 $ 62,390 $ 52,800 $ 215,600 $ 17,740 $ 4,435 CCPPR ($/Percent Fuel Consumption Benefit) Aero $ 1,636 $ — $ — $ — $ — $ — $ 33 Engine $ 1,352 $ 1,144 $ 1,144 $ 1,171 $ 1,144 $ 1,352 $ 214 Weight $ 8,000 $ 795 $ 795 $ - $ 1,600 $ 4,286 $ 563 Tire $ 200 $ 167 $ 167 $ 200 $ 300 $ 133 $ 10 Transmission $ 1,040 $ 133 $ 133 $ 133 $ 133 $ 150 $ 244 Hybrid $

— $ 1,727 $ 1,429 $ 2,000 $ 6,667 $ — $ — Mgmt $ 333 $ — $ — $ — $ — $ — $ — Idle Reduction $ 1,333 $ — $ — $ — $ — $ — $ — All Strategies $ 1,475 $ 1,652 $ 1,552 $ 1,859 $ 5,890 $ 1,268 $ 207

a Does not include fuel consumption penalty associated wi th added weight of fuel savings technologies b Added weight of fuel savings technologies

c Assumes that 80% of fuel is used on road, and 20% is used at id le. This de-rates the fuel consumption benefit of all technologi es,

except for the hybrid. For the near term packages, the projected fuel co nsumption benefits range from 14 to 42 percent, while costs range from $4,000 (for the Class 2b pickup and van segment) to $215,000 (for the transit bus, which includes a high-cost hybrid syst em). However, most of the vehicle classes lie in a relatively narrow band that shows 30 to 40 percent improvement at capital costs that range5-8 from $40,000 to $60,000. The CCPPR of these pack ages is $600 to $1,100 per percent benefit for four of the vehicle classes, but ranges from $56 (for Class 2b vehicles) to $3,600 per percent (for transit buses).

Table 5-9. Fuel consumption reduction, capital cost, and CCPPR - 2015 to 2020 vehicle technology

TT Box Bucket d Refuse Bus Coach 2b Fuel Consumption Reduction
Aero 11.5% 6%

— — — 8% 3% Engine 20% 14% 11.2% 14% 14% 20% 23% Weight 1.25% 4% 3.2% 1% 6.25% 1.05% 0.75%
Tire 11% 3% 2.4% 2.5% 1.5% 3% 2%
Transmission 7% 4% 3.2% 4% 4% 4.5% 7.5% Hybrid 10% 30% 40% 25% 35%

— 18% Mgmt 6%

— — — — — — Idle Reduction a

— — — — — — — Subtotal b 51.0% 49.4% 51.3% 40.2% 50.4% 32.5% 44.9% Added Wt (lb) c 2,030 1,100 1,050 1, 500 2,000 1,100 300 Adj. FC Total 50.5% 47.1% 49. 6% 38.4% 47.8% 32.0% 44.5% Capital Cost Aero $ 12,000 $ 3,250 $ - $ - $ - $ 4,500 $ 100 Engine $ 23,000 $ 13,000 $ 13,000 $ 14,800 $ 13,000 $ 23,000 $ 4,000 Weight $ 13,500 $ 4,770 $ 4,770 $ 3,000 $ 15,300 $ 6,000 $ 600 Tire $ 3,600 $ 300 $ 300 $ 300 $ 300 $ 450 $ 10 Transmission $ 5,800 $ 1,800 $ 1,800 $ 2,700 $ 1,800 $ 2,400 $ 1,000 Hybrid $ 25,000 $ 20,000 $ 30,000 $ 30,000 $ 220,000 $

— $ 9,000 Mgmt $ 1,700 $

—$

— $

— $

—$

— $

— Idle Reduction a $

— $

—$

— $

— $

— $

— $

— Total $ 84,600 $ 43,120 $ 49,870 $ 50,800 $ 250,400 $ 36,350 $ 14,710 CCPPR ($/Percent Fuel Consumption Benefit) Aero $ 1,043 $ 542 $ - $ - $ - $ 563 $ 33 Engine $ 1,150 $ 929 $ 929 $ 1,057 $ 929 $ 1,150 $ 174 Weight $ 10,800 $ 1,193 $ 1,193 $ 3,000 $ 2,448 $ 5,714 $ 800 Tire $ 327 $ 100 $ 100 $ 120 $ 200 $ 150 $ 5 Transmission $ 829 $ 450 $ 450 $ 675 $ 450 $ 533 $ 133 Hybrid $ 2,500 $ 667 $ 750 $ 1,200 $ 6,286 $

— $ 500 Mgmt $ 283 $

— $

— $

— $

— $

— $

— Idle Reduction a $

— $

— $

— $

— $

— $

— $

— All Packages $ 1,674 $ 915 $ 1006 $ 1,323 $ 5,232 $ 1,135 $ 331

a Overnight idle reduction is assumed to be implemented as part of the hybrid package b Does not include fuel consumption penalty associated with added weight of f uel savings technologies
c Added weight of fuel savings technologies d Assumes that 80% of fuel is used on road, and 20% is used at idle5-9 Table 5-9 summarizes the indivi dual results shown in Tables 5-1 through 5-7 into a format similar to Table 5-8 for the 2013-2015 technologies. This table gives similar set of metrics for technologies that will be market viable be tween 2015 and 2020. The technologies in this timeframe include a second gene ration hybrid system at lower cost for urban vehicles; and advanced aerodynamic improvements coupled with a bottoming cycle to recover waste heat on highway vehicles.
The 2015-2020 packages reduce fuel consumption by 30 to 50 percent; all of the technologies with the exception of the motor coach range ar e over 40 percent. The costs of these packages range from $14,000 (Class 2b) to $250,000 (transit bus). However, the other applications lie in a narrow band from $40,000 to $85,000. Many of the technologies benefi t from anticipated reductions in the cost of hybrid vehicles duri ng this timeframe. The 2015-2020 technologies have higher CCPPR than the 2013-2015 packages. Esti mates range from $250 to $5,000 per percent improvement, depending on vehicle class. For five of the seven vehicle classes, the benefits lie in a range from $500 to $1,700 per percent fuel consumption reduction.
It needs to be emphasized that these results are very dependent on the vehi cle’s duty cycle and as such should be viewed as averages for each truc k segment. Further, although the data for this analysis were obtained for the specific truck segmen ts and, in general, for typical duty cycles for these segments, detailed vehi cle stimulation modeling was no t done to establish the fuel consumption benefits. Follow up work is needed to confirm not only the individual estimated benefits for each technology, but also the packaged benefits. We recommend, therefore, that our analysis be extended by modeling actual vehicle technologies identified in this analysis to appropriately capture the synergie s of complex vehicle systems.
Although the cumulative benefits and capital costs for vehicles clas ses are relatively similar, the likely pathway to achieve these benefits varies considerably. For line-haul vehicles, waste-heat recovery and aerodynamics represent the larges t opportunities, but high single-digit gains are possible in nearly every category. For urban vehicles (box & bucket, buses, and refuse), hybridization provides the bulk of the benefit. In addition, engine optimization provides significant benefits to all vehicle classes. Figure 5-1 illustrates the importance of all technologies for tractor trailer applications and the importan ce of hybrid systems for those applications that are dominated by stop a nd go duty cycles or extended PTO operation.

To characterize these differences in the technolo gy effectiveness of different strategies across vehicle segments, each strategy was ranked in orde r of CCPPR for each vehi cle class. These data were then used to generate cost-cur ves as shown in Figures 5-2 and 5-3.
TIAX’s analysis shows that there is potential to achieve fuel consumption benefits of 40 to 50 percent across a broad subset of the medium - and heavy-duty vehicl e fleet between 2015 and 2020, at costs that range from $40,000 to $90,000. Th e technologies used to achieve these benefits vary by segment: on urban vehicles, bene fits are largely driven by hybridization, while on-highway vehicles achieve be nefits through waste-heat r ecovery and aerodynamics. We speculate that some, but not all, of these fuel consumption benefits wi ll be achieved without regulation. A commonly cited rule of thumb is that line-haul tractor trailer fleets will pay $900 for 1 percent of efficiency improvement. Our analysis shows that 30 percent efficiency improvement can be achieved at a CCPPRof $64 0 per percent, while 50 percent efficiency5-10 0% 10% 20% 30% 40% 50% 60%

TT Box Bucket Refuse Bus Coach 2bFC Benefit Aero Engine Weight Tires & Wheels Transmission Hybrid Mgmt & Coaching

Figure 5-1. Comparison of Fuel Savings Technology for Tractor Trailer (TT), Class 3-6 Box (Box), Class 3-6 Bucket (Bucket), Class 8 Refuse (Refuse), Transit Bus (Bus), Motor Coach (Coach), and Class 2b Pickups and Vans (2b)

$- $20,000 $40,000 $60,000 $80,000 $100,000

0% 5% 10% 15% 20% 25% 30% 35% 40% 45%
% BenefitPackage Cost Tractor-Trailer Straight Box
Bucket Refuse
Bus Coach Class 2b

Figure 5-2. Cost curves for 2013-2015 packages. The transit bus extends to $215,000 at a benefit of 40 percent5-11 $- $10,000 $20,000 $30,000 $40,000 $50,000 $60,000 $70,000 $80,000 $90,000 $100,000

0% 10% 20% 30% 40% 50% 60%
% BenefitPackage Cost Tractor-Trailer Straight Box Bucket Refuse Bus Coach Class 2b

Figure 5-3. Cost curves for 2015-2020 packages. The transit bus extends to $250,000 at a benefit of 50 percent

improvement is achieved at a CCPPR of $1,700 pe r percent. In other vehicle segments, which have lower mileage, fuel efficiency is commonly valued at $250 per percent. In these segments, adoption is likely to be much lower. We project that in se veral segments, 50 percent fuel efficiency can be achieved at a cost of $500 to $900 per percent.

5.2 Payback Analysis
For the purposes of this evaluation, we compare paybacks for two fuel price scenarios: $4.00 and $3.00 per gallon (gasoline or diesel). Vehicle classifications that we compared are Class 8 linehaul tractor trailer, tr ansit bus, refuse hauler and Class 3-6 box truck. Table 5-10 compares the mileage, average speed, driver characteristics, fuel economy, and fuel consumption for the four applications. Also shown is what a 1 percent re duction in fuel consumption would be and the savings that would result by reducing fu el consumption by that 1 percent.

For each vehicle class we dete rmined the fuel savings for the 2015-2020 technologies from the percent fuel consumption benefit shown in Table 5-9. Annual dolla r savings were then estimated for $4 per gallon diesel fuel and fo r $3 per gallon diesel fuel. These fuel savings were compared to the total costs of the technol ogy to determine the payback in years and months. The results are shown in Table 5-11. This payback estim ate does not include any other operating and maintenance (O&M) costs or savings associated w ith the added fuel economy technologies. This analysis was done to provide a first cut estimate of payback. A more sophisticated discount5-12 Table 5-10. Operational characteristics for payback evaluation

Fleet Characteristics Tractor Trailer Transit Bus Refuse Hauler Class 3-6 Van Annual Mileage (miles per year) 120,000 40,000 25,000 60,000 Average speed (miles per hour) 46.2 12 12 28.8 Driver work week (days per week) 6 5 5 5 Driver time (hours per week) 50 64 a 40 40 Fuel economy (miles per gallon) 6.5 3.5 3.3 8 Fuel consumption (gallons per year) 18,500 11,400 7,600 7,500 1% Fuel consumption savings (gal per yr) 185 114 76 75

Fuel cost savings for 1% reduction (@$4/gal diesel) $738 $457 $303 $300

Fuel cost savings for 1% reduction (at $3/gal diesel) $554 $343 $227 $225

a On average bus will be operated by more than one driver

Table 5-11 Simple Payback Analysis for Selected Vehicle Applications

Cost Item Tractor Trailer 40 Ft Transit Bus Refuse Hauler Class 3-6 Box Technology Costs ($) 84,600 250,400 50,800 43,120 Annual Fuel used (gal) 18,500 11,400 7,600 7,500 FC savings (%) 50.5 47.9 38.4 47.1 Fuel saved (gal) 9,350 5,456 2,918 3,534 $4 per gallon Diesel Price Annual $ saved 37,402 21,825 11,672 14,136 Payback (yrs) 2.3 11.5 4.4 3.1 Payback (months) 27.1 137.7 52.2 36.6 $3 per gallon Diesel Price Annual $ saved 28,051 16,369 8,754 10,602 Payback (yrs) 3.0 15.3 5.8 4.1 Payback (months) 36.2 183.6 69.6 48.8

analysis is needed and this analysis should include time value of m oney, O&M costs, other owner’s costs such as insurance and ex cise taxes, and any replacement costs.5-13 As shown the payback periods for vehicle applic ations except transit bus es range from 2 to 4 years at $4 per gallon diesel price and from 3 to 6 years at $3 per gallon diesel price. Without Federal funding, the costs of tran sit buses and, in particular, the incremental cost of hybrid buses, the payback periods at either fuel price are quite high. With Federa l funding covering the majority of the upfront hardware costs, th e incremental technology costs reduce to $52,400 and the corresponding paybacks are 2.4 years for $4 diesel and 3.2 years for $3 diesel. This is more in line with the other vehicle applications.
These estimated paybacks are only a first cut of the possible economics of fuel savings technologies. In this first cut, we included all technol ogies that could be av ailable in the 2015 to 2020 period. This represents the maximum benefit for each application but also the highest cost. We did not try to apply the technologies ba sed on the best CCPPR—adding lowest CCPPR technologies first followed by the more expensive t echnologies. Finally, we also have to caution that the fuel consumption benefits were comb ined without the benefit of vehicle simulation modeling and estimated benefits could increase or decrease depending on the integration of these technologies.
We feel these payback periods are probably margin al and would have to be lower for users to adopt these packages of fuel savings technologie s without any other mitigating factors. Also there other O&M cost savings like reduced brake wear that could reduce payback periods. This analysis was done to get an ideal of whether the capital cost and be nefits were in the ballpark of being acceptable. We believe this to be the ca se, but a more sophisticat ed life cycle costing is necessary.A-1 Appendix A. References

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Site Visits:

April 8, 2009 Ford Motor Company April 8, 2009 Daimler Trucks North America, Detroit Diesel April 8, 2009 Azure Dynamics April 8, 2009 Eaton April 8, 2009 Arvin Meritor April 8, 2009 TARDEC April 9, 2009 Navistar May 4, 2009 PACCAR May 7, 2009 ISE Corporation May 13, 2009 Volvo Trucks NA May 14, 2009 Allison Transmissions May 15, 2009 Cummins Engine Company July 22, 2009 Peterbilt Trucks, Great Dane Trailers, Wal-Mart August 11, 2009 Auto Research Center August 12, 2009 Transportation Research Center

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