7.8
                                      7.8
                                      7.8
                                      7.8
                                      7.8
                                    Level 1
                                      6.6
                                      6.6
                                      6.6
                                      6.6
                                      6.6
                                      6.6
                                      6.6
                                      6.6
                                      6.6
                                    Level 2
                                      5.7
                                      5.7
                                      5.7
                                      5.7
                                      5.7
                                      5.7
                                      5.7
                                      5.7
                                      5.7
                                    Level 3
                                      4.3
                                      4.3
                                      4.3
                                      4.3
                                      4.3
                                      4.3
                                      4.3
                                      4.3
                                      4.3
                      Drive Tires (CRR in kg/metric ton)
                                     Base
                                      8.2
                                      8.2
                                      8.2
                                      8.2
                                      8.2
                                      8.2
                                      8.2
                                      8.2
                                      8.2
                                    Level 1
                                      7.0
                                      7.0
                                      7.0
                                      7.0
                                      7.0
                                      7.0
                                      7.0
                                      7.0
                                      7.0
                                    Level 2
                                      6.0
                                      6.0
                                      6.0
                                      6.0
                                      6.0
                                      6.0
                                      6.0
                                      6.0
                                      6.0
                                    Level 3
                                      4.5
                                      4.5
                                      4.5
                                      4.5
                                      4.5
                                      4.5
                                      4.5
                                      4.5
                                      4.5
                         Idle Reduction (% reduction)
                                      APU
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                      5%
                                      5%
                                      5%
                                     Other
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                      7%
                                      7%
                                      7%
                        Transmission Type (% reduction)
                                    Manual
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                      AMT
                                      2%
                                      2%
                                      2%
                                      2%
                                      2%
                                      2%
                                      2%
                                      2%
                                      2%
                                     Auto
                                      2%
                                      2%
                                      2%
                                      2%
                                      2%
                                      2%
                                      2%
                                      2%
                                      2%
                                  Dual Clutch
                                      2%
                                      2%
                                      2%
                                      2%
                                      2%
                                      2%
                                      2%
                                      2%
                                      2%
                            Driveline (% reduction)
                                Axle Lubricant
                                     0.5%
                                     0.5%
                                     0.5%
                                     0.5%
                                     0.5%
                                     0.5%
                                     0.5%
                                     0.5%
                                     0.5%
                                6x2 or 4x2 Axle
                                     2.5%
                                     2.5%
                                     2.5%
                                     2.5%
                                     2.5%
                                     2.5%
                                     2.5%
                                     2.5%
                                     2.5%
                                   Downspeed
                                     1.8%
                                     1.8%
                                     1.8%
                                     1.8%
                                     1.8%
                                     1.8%
                                     1.8%
                                     1.8%
                                     1.8%
                     Accessory Improvements (% reduction)
                                     A/C
                                     0.5%
                                     0.5%
                                     0.5%
                                     0.5%
                                     0.5%
                                     0.5%
                                     0.5%
                                     0.5%
                                     0.5%
                               Electric Access.
                                      1%
                                      1%
                                      1%
                                      1%
                                      1%
                                      1%
                                      1%
                                      1%
                                      1%
                Predefined Off-Cycle Technologies (% reduction)
                           Predictive Cruise Control
                                      2%
                                      2%
                                      2%
                                      2%
                                      2%
                                      2%
                                      2%
                                      2%
                                      2%
                        Automated Tire Inflation System
                                      1%
                                      1%
                                      1%
                                      1%
                                      1%
                                      1%
                                      1%
                                      1%
                                      1%

    Tractor Technology Adoption Rates
As explained above, tractor manufacturers often introduce major product changes together, as a package.  In this manner the manufacturers can optimize their available resources, including engineering, development, manufacturing and marketing activities to create a product with multiple new features.  In addition, manufacturers recognize that a truck design will need to remain competitive over the intended life of the design and meet future regulatory requirements.  In some limited cases, manufacturers may implement an individual technology outside of a vehicle's redesign cycle.
With respect to the levels of technology adoption used to develop the proposed HD Phase 2 standards, NHTSA and EPA established technology adoption constraints. The first type of constraint was established based on the application of fuel consumption and CO2 emission reduction technologies into the different types of tractors.  For example, extended idle reduction technologies are limited to Class 8 sleeper cabs using the reasonable assumption that day cabs are not used for overnight hoteling.  A second type of constraint was applied to most other technologies and limited their adoption based on factors reflecting the real world operating conditions that some combination tractors encounter.  This second type of constraint was applied to the aerodynamic, tire, powertrain, and vehicle speed limiter technologies.  Table III-8,
Table III-9, and Table III-10, specify the adoption rates that EPA and NHTSA used to develop the proposed standards.
NHTSA and EPA believe that within each of these individual vehicle categories there are particular applications where the use of the identified technologies would be either ineffective or not technically feasible.  For example, the agencies are not predicating the proposed standards on the use of full aerodynamic vehicle treatments on 100 percent of tractors because we know that in many applications (for example gravel truck engaged in local aggregate delivery) the added weight of the aerodynamic technologies will increase fuel consumption and hence CO2 emissions to a greater degree than the reduction that would be accomplished from the more aerodynamic nature of the tractor.
Aerodynamics Adoption Rate
The impact of aerodynamics on a tractor-trailer's efficiency increases with vehicle speed.  Therefore, the usage pattern of the vehicle will determine the benefit of various aerodynamic technologies.  Sleeper cabs are often used in line haul applications and drive the majority of their miles on the highway travelling at speeds greater than 55 mph.  The industry has focused aerodynamic technology development, including SmartWay tractors, on these types of trucks.  Therefore the agencies are proposing the most aggressive aerodynamic technology application to this regulatory subcategory.  All of the major manufacturers today offer at least one SmartWay sleeper cab tractor model, which is represented as Bin III aerodynamic performance.  The proposed aerodynamic adoption rate for Class 8 high roof sleeper cabs in 2027 (i.e., the degree of technology adoption on which the stringency of the proposed standard is premised) consists of 20 percent of Bin IV, 35 percent Bin V, 20 percent Bin VI, and 5 percent Bin VII reflecting our assessment of the fraction of tractors in this segment that could successfully apply these aerodynamic packages with this amount of lead time.  We believe that there is sufficient lead time to develop aerodynamic tractors that can move the entire high roof sleeper cab aerodynamic performance to be as good as or better than today's SmartWay designated tractors.  The changes required for Bin IV and better performance reflect the kinds of improvements projected in the Department of Energy's SuperTruck program.  That program assumes that such systems can be demonstrated on vehicles by 2017.  In this case, the agencies are projecting that truck manufacturers would be able to begin implementing these aerodynamic technologies as early as 2021 MY on a limited scale.  Importantly, our averaging, banking and trading provisions provide manufacturers with the flexibility (and incentive) to implement these technologies over time even though the standard changes in a single step.
The aerodynamic adoption rates used to develop the proposed standards for the other tractor regulatory categories are less aggressive than for the Class 8 sleeper cab high roof.  Aerodynamic improvements through new tractor designs and the development of new aerodynamic components is an inherently slow and iterative process.  The agencies recognize that there are tractor applications which require on/off-road capability and other truck functions which restrict the type of aerodynamic equipment applicable.  We also recognize that these types of trucks spend less time at highway speeds where aerodynamic technologies have the greatest benefit.  The 2002 VIUS data ranks trucks by major use.  The heavy trucks usage indicates that up to 35 percent of the trucks may be used in on/off-road applications or heavier applications.  The uses include construction (16 percent), agriculture (12 percent), waste management (5 percent), and mining (2 percent).  Therefore, the agencies analyzed the technologies to evaluate the potential restrictions that would prevent 100 percent adoption of more advanced aerodynamic technologies for all of the tractor regulatory subcategories.
As discussed in Section III.C.2, the agencies propose to increase the number of aerodynamic bins for low and mid roof tractors from the two levels adopted in Phase 1 to four levels in Phase 2.  The agencies propose to increase the number of bins for these tractors to reflect the actual range of aerodynamic technologies effective in low and mid roof tractor applications.  The aerodynamic improvements to the bumper, hood, windshield, mirrors, and doors are developed for the high roof tractor application and then carried over into the low and mid roof applications.
Low Rolling Resistance Tire Adoption Rate
For the tire manufacturers to further reduce tire rolling resistance, the manufacturers must consider several performance criteria that affect tire selection.  The characteristics of a tire also influence durability, traction control, vehicle handling, comfort, and retreadability.  A single performance parameter can easily be enhanced, but an optimal balance of all the criteria will require improvements in materials and tread design at a higher cost, as estimated by the agencies.  Tire design requires balancing performance, since changes in design may change different performance characteristics in opposing directions.  Similar to the discussion regarding lesser aerodynamic technology application in tractor segments other than sleeper cab high roof, the agencies believe that the proposed standards should not be premised on 100 percent application of Level IV tires in all tractor segments given the potential interference with vehicle utility that could result.
Weight Reduction Technology Adoption Rate
Unlike in HD Phase 1, the agencies propose setting the 2021 through 2027 model year tractor standards without using weight reduction as a technology to demonstrate the feasibility.  However, as described in Section III.C.2 below, the agencies are proposing an expanded list of weight reduction options which could be input into the GEM by the manufacturers to reduce their certified CO2 emission and fuel consumption levels.  The agencies view weight reduction as a technology with a high cost that offers a small benefit in the tractor sector.  For example, our estimate of a 400 pound weight reduction would cost $2,050 (2012$) in 2021MY, but offers a 0.3 percent reduction in fuel consumption and CO2 emissions.
Idle Reduction Technology Adoption Rate
Idle reduction technologies provide significant reductions in fuel consumption and CO2 emissions for Class 8 sleeper cabs and are available on the market today.  There are several different technologies available to reduce idling.  These include APUs, diesel fired heaters, and battery powered units.  Our discussions with manufacturers indicate that idle technologies are sometimes installed in the factory, but it is also a common practice to have the units installed after the sale of the truck.  We would like to continue to incentivize this practice and to do so in a manner that the emission reductions associated with idle reduction technology occur in use.  Therefore, as adopted in Phase 1, we are allowing only idle emission reduction technologies which include an automatic engine shutoff (AES) with some override provisions.  However, we welcome comment on other approaches that would appropriately quantify the reductions that would be experienced in the real world.
We propose an overall 90 percent adoption rate for this technology for Class 8 sleeper cabs.  The agencies are unaware of reasons why AES with extended idle reduction technologies could not be applied to this high fraction of tractors with a sleeper cab, except those deemed a vocational tractor, in the available lead time.
The agencies are interested in extending the idle reduction benefits beyond Class 8 sleepers, to day cabs. The agencies reviewed literature to quantify the amount of idling which is conducted outside of hoteling operations.  One study, conducted by Argonne National Laboratory, identified several different types of trucks which might idle for extended amounts of time during the work day.  Idling may occur during the delivery process, queuing at loading docks or border crossings, during power take off operations, or to provide comfort during the work day.  However, the study provided only "rough estimates" of the idle time and energy use for these vehicles.  The agencies are not able to appropriately develop a baseline of workday idling for day cabs and identify the percent of this idling which could be reduced through the use of AES.  We welcome comment and data on quantifying the effectiveness of AES on day cabs.
Vehicle Speed Limiter Adoption Rate
As adopted in Phase 1, we propose to continue the approach where vehicle speed limiters may be used as a technology to meet the proposed standard.  In setting the proposed standard, however, we assumed a zero percent adoption rate of vehicle speed limiters.  Although we believe vehicle speed limiters are a simple, easy to implement, and inexpensive technology, we want to leave the use of vehicles speed limiters to the truck purchaser.  Since truck fleets purchase tractors today with owner-set vehicle speed limiters, we considered not including VSLs in our compliance model.  However, we have concluded that we should allow the use of VSLs that cannot be overridden by the operator as a means of compliance for vehicle manufacturers that wish to offer it and truck purchasers that wish to purchase the technology.  In doing so, we are providing another means of meeting that standard that can lower compliance cost and provide a more optimal vehicle solution for some truck fleets.  For example, a local beverage distributor may operate trucks in a distribution network of primarily local roads.  Under those conditions, aerodynamic fairings used to reduce aerodynamic drag provide little benefit due to the low vehicle speed while adding additional mass to the vehicle.  A vehicle manufacturer could choose to install a VSL set at 55 mph for this customer.  The resulting tractor would be optimized for its intended application and would be fully compliant with our program all at a lower cost to the ultimate tractor purchaser.
As in Phase 1, we have chosen not to base the proposed standards on performance of VSLs because of concerns about how to set a realistic adoption rate that avoids unintended adverse impacts.  Although we expect there would be some use of VSL, currently it is used when the fleet involved decides it is feasible and practicable and increases the overall efficiency of the freight system for that fleet operator.  To date, the compliance data provided by manufacturers indicate that none of the tractor configurations include a tamper-proof VSL setting less than 65 mph.  At this point the agencies are not in a position to determine in how many additional situations use of a VSL would result in similar benefits to overall efficiency or how many customers would be willing to accept a tamper-proof VSL setting.  As discussed in Section III.E.2.f below, we welcome comment on suggestions to modify the tamper-proof requirement while maintaining assurance that the speed limiter is used in-use throughout the life of the vehicle.  We are not able at this time to quantify the potential loss in utility due to the use of VSLs.  Absent this information, we cannot make a determination regarding the reasonableness of setting a standard based on a particular VSL level.  Therefore, the agencies are not premising the proposed standards on use of VSL, and instead would continue to rely on the industry to select VSL when circumstances are appropriate for its use.  The agencies have not included either the cost or benefit due to VSLs in analysis of the proposed program's costs and benefits, therefore it remains a significant flexibility for manufacturers to choose.
Summary of the Adoption Rates used to Determine the Proposed Standards
Table III-8,
Table III-9 and Table III-10 provide the adoption rates of each technology broken down by weight class, cab configuration, and roof height.
Table III-8 Technology Adoption Rates for Class 7 and 8 Tractors for Determining the Proposed 2021 MY Standards

                                    Class 7
                                    Class 8

                                    Day Cab
                                    Day Cab
                                  Sleeper Cab

                                   Low Roof
                                   Mid Roof
                                   High Roof
                                   Low Roof
                                   Mid Roof
                                   High Roof
                                   Low Roof
                                   Mid Roof
                                   High Roof
                       2021MY Engine Technology Package

                                     100%
                                     100%
                                     100%
                                     100%
                                     100%
                                     100%
                                     100%
                                     100%
                                     100%
                                 Aerodynamics
                                     Bin I
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                    Bin II
                                      75%
                                      75%
                                      0%
                                      75%
                                      75%
                                      0%
                                      75%
                                      75%
                                      0%
                                    Bin III
                                      25%
                                      25%
                                      40%
                                      25%
                                      25%
                                      40%
                                      25%
                                      25%
                                      40%
                                    Bin IV
                                      0%
                                      0%
                                      35%
                                      0%
                                      0%
                                      35%
                                      0%
                                      0%
                                      35%
                                     Bin V
                                      N/A
                                      N/A
                                      20%
                                      N/A
                                      N/A
                                      20%
                                      N/A
                                      N/A
                                      20%
                                    Bin VI
                                      N/A
                                      N/A
                                      5%
                                      N/A
                                      N/A
                                      5%
                                      N/A
                                      N/A
                                      5%
                                    Bin VII
                                      N/A
                                      N/A
                                      0%
                                      N/A
                                      N/A
                                      0%
                                      N/A
                                      N/A
                                      0%
                                 Steer Tires
                                     Base
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                    Level 1
                                      60%
                                      60%
                                      60%
                                      60%
                                      60%
                                      60%
                                      60%
                                      60%
                                      60%
                                    Level 2
                                      25%
                                      25%
                                      25%
                                      25%
                                      25%
                                      25%
                                      25%
                                      25%
                                      25%
                                    Level 3
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                 Drive Tires
                                     Base
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                    Level 1
                                      60%
                                      60%
                                      60%
                                      60%
                                      60%
                                      60%
                                      60%
                                      60%
                                      60%
                                    Level 2
                                      25%
                                      25%
                                      25%
                                      25%
                                      25%
                                      25%
                                      25%
                                      25%
                                      25%
                                    Level 3
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                           Extended Idle Reduction
                                      APU
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                      80%
                                      80%
                                      80%
                              Transmission Type
                                    Manual
                                      45%
                                      45%
                                      45%
                                      45%
                                      45%
                                      45%
                                      45%
                                      45%
                                      45%
                                      AMT
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                     Auto
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                  Dual Clutch
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                  Driveline
                                Axle Lubricant
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                6x2 or 4x2 Axle

                                      10%
                                      10%
                                      20%
                                      10%
                                      10%
                                      20%
                                   Downspeed
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                            Accessory Improvements
                                      A/C
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                               Electric Access.
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                      Predefined Off-Cycle Technologies
                           Predictive Cruise Control
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                        Automated Tire Inflation System
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%

Table III-9 Technology Adoption Rates for Class 7 and 8 Tractors for Determining the Proposed 2024 MY Standards

                                    Class 7
                                    Class 8

                                    Day Cab
                                    Day Cab
                                  Sleeper Cab

                                   Low Roof
                                   Mid Roof
                                   High Roof
                                   Low Roof
                                   Mid Roof
                                   High Roof
                                   Low Roof
                                   Mid Roof
                                   High Roof
                       2024 MY Engine Technology Package

                                     100%
                                     100%
                                     100%
                                     100%
                                     100%
                                     100%
                                     100%
                                     100%
                                     100%
                                 Aerodynamics
                                     Bin I
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                    Bin II
                                      60%
                                      60%
                                      0%
                                      60%
                                      60%
                                      0%
                                      60%
                                      60%
                                      0%
                                    Bin III
                                      38%
                                      38%
                                      30%
                                      38%
                                      38%
                                      30%
                                      38%
                                      38%
                                      30%
                                    Bin IV
                                      2%
                                      2%
                                      30%
                                      2%
                                      2%
                                      30%
                                      2%
                                      2%
                                      30%
                                     Bin V
                                      N/A
                                      N/A
                                      25%
                                      N/A
                                      N/A
                                      25%
                                      N/A
                                      N/A
                                      25%
                                    Bin VI
                                      N/A
                                      N/A
                                      13%
                                      N/A
                                      N/A
                                      13%
                                      N/A
                                      N/A
                                      13%
                                    Bin VII
                                      N/A
                                      N/A
                                      2%
                                      N/A
                                      N/A
                                      2%
                                      N/A
                                      N/A
                                      2%
                                 Steer Tires
                                     Base
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                    Level 1
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                    Level 2
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                                    Level 3
                                      15%
                                      15%
                                      15%
                                      15%
                                      15%
                                      15%
                                      15%
                                      15%
                                      15%
                                 Drive Tires
                                     Base
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                    Level 1
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                    Level 2
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                                    Level 3
                                      15%
                                      15%
                                      15%
                                      15%
                                      15%
                                      15%
                                      15%
                                      15%
                                      15%
                           Extended Idle Reduction
                                      APU
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                      90%
                                      90%
                                      90%
                              Transmission Type
                                    Manual
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      AMT
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                     Auto
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                  Dual Clutch
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                  Driveline
                                Axle Lubricant
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                6x2 or 4x2 Axle

                                      20%
                                      20%
                                      60%
                                      20%
                                      20%
                                      60%
                                   Downspeed
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                 Direct Drive
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                            Accessory Improvements
                                      A/C
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                               Electric Access.
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                      Predefined Off-Cycle Technologies
                           Predictive Cruise Control
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                        Automated Tire Inflation System
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%

Table III-10 Technology Adoption Rates for Class 7 and 8 Tractors for Determining the Proposed 2027 MY Standards

                                    Class 7
                                    Class 8

                                    Day Cab
                                    Day Cab
                                  Sleeper Cab

                                   Low Roof
                                   Mid Roof
                                   High Roof
                                   Low Roof
                                   Mid Roof
                                   High Roof
                                   Low Roof
                                   Mid Roof
                                   High Roof
                       2027 MY Engine Technology Package

                                     100%
                                     100%
                                     100%
                                     100%
                                     100%
                                     100%
                                     100%
                                     100%
                                     100%
                                 Aerodynamics
                                     Bin I
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                    Bin II
                                      50%
                                      50%
                                      0%
                                      50%
                                      50%
                                      0%
                                      50%
                                      50%
                                      0%
                                    Bin III
                                      40%
                                      40%
                                      20%
                                      40%
                                      40%
                                      20%
                                      40%
                                      40%
                                      20%
                                    Bin IV
                                      10%
                                      10%
                                      20%
                                      10%
                                      10%
                                      20%
                                      10%
                                      10%
                                      20%
                                     Bin V
                                      N/A
                                      N/A
                                      35%
                                      N/A
                                      N/A
                                      35%
                                      N/A
                                      N/A
                                      35%
                                    Bin VI
                                      N/A
                                      N/A
                                      20%
                                      N/A
                                      N/A
                                      20%
                                      N/A
                                      N/A
                                      20%
                                    Bin VII
                                      N/A
                                      N/A
                                      5%
                                      N/A
                                      N/A
                                      5%
                                      N/A
                                      N/A
                                      5%
                                 Steer Tires
                                     Base
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                    Level 1
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                    Level 2
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                    Level 3
                                      25%
                                      25%
                                      25%
                                      25%
                                      25%
                                      25%
                                      25%
                                      25%
                                      25%
                                 Drive Tires
                                     Base
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                      5%
                                    Level 1
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                      20%
                                    Level 2
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                    Level 3
                                      25%
                                      25%
                                      25%
                                      25%
                                      25%
                                      25%
                                      25%
                                      25%
                                      25%
                           Extended Idle Reduction
                                      APU
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                      90%
                                      90%
                                      90%
                              Transmission Type
                                    Manual
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      AMT
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                     Auto
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                                  Dual Clutch
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                      10%
                                  Driveline
                                Axle Lubricant
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                   6x2 Axle

                                      20%
                                      20%
                                      60%
                                      20%
                                      20%
                                      60%
                                   Downspeed
                                      60%
                                      60%
                                      60%
                                      60%
                                      60%
                                      60%
                                      60%
                                      60%
                                      60%
                                 Direct Drive
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                                      50%
                            Accessory Improvements
                                      A/C
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                               Electric Access.
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                                      30%
                      Predefined Off-Cycle Technologies
                           Predictive Cruise Control
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                        Automated Tire Inflation System
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%
                                      40%

     Derivation of the Proposed Tractor Standards
The agencies used the technology effectiveness inputs and technology adoption rates to develop GEM inputs to derive the proposed HD Phase 2 fuel consumption and CO2 emissions standards for each subcategory of Class 7 and 8 combination tractors.  Note that we have analyzed one technology pathway for each proposed level of stringency, but manufacturers would be free to use any combination of technology to meet the standards, and with the flexibility of averaging, banking and trading, to meet the standard on average.  The agencies derived a scenario tractor for each subcategory by weighting the individual GEM input parameters included in Table III-7 with the adoption rates in Table III-8,
Table III-9, and Table III-10.  For example, the proposed CdA value for a 2021MY Class 8 Sleeper Cab High Roof scenario case was derived as 40 percent times 6.3 plus 35 percent times 5.6 plus 20 percent times 5.1 plus 5 percent times 4.7, which is equal to a CdA of 5.74 m[2].  Similar calculations were made for tire rolling resistance, transmission types, idle reduction, and other technologies.  To account for the proposed engine standards and engine technologies, the agencies assumed a compliant engine fuel map in GEM.  The agencies then ran GEM with a single set of vehicle inputs, as shown in Table III-11, to derive the proposed standards for each subcategory.  Additional detail is provided in the draft RIA Chapter 2.
Table III-11 GEM Inputs for the Proposed 2021MY Class 7 and 8 Tractor Standard Setting
                                    Class 7
                                    Class 8
                                    Day Cab
                                    Day Cab
                                  Sleeper Cab
                                   Low Roof
                                   Mid Roof
                                   High Roof
                                   Low Roof
                                   Mid Roof
                                   High Roof
                                   Low Roof
                                   Mid Roof
                                   High Roof
                                    Engine
                           2021MY 11L Engine  350 HP
                           2021MY 11L Engine 350 HP
                           2021MY 11L Engine 350 HP
                           2021MY 15L Engine  455 HP
                           2021MY 15L Engine 455 HP
                           2021MY 15L Engine 455 HP
                           2021MY 15L Engine 455 HP
                           2021MY 15L Engine 455 HP
                           2021MY 15L Engine 455 HP
                          Aerodynamics (CdA in m[2])
                                     4.68
                                     6.08
                                     5.94
                                     4.68
                                     6.08
                                     5.94
                                     4.68
                                     6.08
                                     5.74
                      Steer Tires (CRR in kg/metric ton)
                                      6.2
                                      6.2
                                      6.2
                                      6.2
                                      6.2
                                      6.2
                                      6.2
                                      6.2
                                      6.2
                      Drive Tires (CRR in kg/metric ton)
                                      6.6
                                      6.6
                                      6.6
                                      6.6
                                      6.6
                                      6.6
                                      6.6
                                      6.6
                                      6.6
                Extended Idle Reduction Weighted Effectiveness
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                     2.5%
                                     2.5%
                                     2.5%
             Transmission = 10 speed Automated Manual Transmission
   Gear Ratios = 12.8, 9.25, 6.76, 4.90, 3.58, 2.61, 1.89, 1.38, 1.00, 0.73
                            Drive axle Ratio = 3.55
                        6x2 Axle Weighted Effectiveness
                                     N/A
                                      N/A
                                      N/A
                                     0.3%
                                     0.3%
                                     0.5%
                                     0.3%
                                     0.3%
                                     0.5%
                     Low Friction Axle Lubrication = 0.1%
                          Transmission benefit = 1.1%
                        Predictive Cruise Control =0.4%
                         Accessory Improvements = 0.1%
                Air Conditioner Efficiency Improvements = 0.1%
                    Automatic Tire Inflation Systems = 0.2%
                          Weight Reduction = 0 pounds

Table III-12 GEM Inputs for the Proposed 2024MY Class 7 and 8 Tractor Standard Setting
                                    Class 7
                                    Class 8
                                    Day Cab
                                    Day Cab
                                  Sleeper Cab
                                   Low Roof
                                   Mid Roof
                                   High Roof
                                   Low Roof
                                   Mid Roof
                                   High Roof
                                   Low Roof
                                   Mid Roof
                                   High Roof
                                    Engine
                           2024MY 11L Engine  350 HP
                           2024MY 11L Engine 350 HP
                           2024MY 11L Engine 350 HP
                           2024MY 15L Engine  455 HP
                           2024MY 15L Engine 455 HP
                           2024MY 15L Engine 455 HP
                           2024MY 15L Engine 455 HP
                           2024MY 15L Engine 455 HP
                           2024MY 15L Engine 455 HP
                          Aerodynamics (CdA in m[2])
                                     4.59
                                     5.99
                                     5.74
                                     4.59
                                     5.99
                                     5.74
                                     4.59
                                     5.99
                                     5.54
                      Steer Tires (CRR in kg/metric ton)
                                      5.9
                                      5.9
                                      5.9
                                      5.9
                                      5.9
                                      5.9
                                      5.9
                                      5.9
                                      5.9
                      Drive Tires (CRR in kg/metric ton)
                                      6.2
                                      6.2
                                      6.2
                                      6.2
                                      6.2
                                      6.2
                                      6.2
                                      6.2
                                      6.2
                Extended Idle Reduction Weighted Effectiveness
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                      3%
                                      3%
                                      3%
             Transmission = 10 speed Automated Manual Transmission
   Gear Ratios = 12.8, 9.25, 6.76, 4.90, 3.58, 2.61, 1.89, 1.38, 1.00, 0.73
                            Drive axle Ratio = 3.36
                        6x2 Axle Weighted Effectiveness
                                      N/A
                                      N/A
                                      N/A
                                     0.5%
                                     0.5%
                                     1.5%
                                     0.5%
                                     0.5%
                                     1.5%
                     Low Friction Axle Lubrication = 0.2%
                          Transmission benefit = 1.6%
                        Predictive Cruise Control =0.8%
                         Accessory Improvements = 0.2%
                Air Conditioner Efficiency Improvements = 0.1%
                    Automatic Tire Inflation Systems = 0.4%
                          Weight Reduction = 0 pounds
   Direct Drive Weighted Efficiency = 1% for sleeper cabs; 0.8% for day cabs

Table III-13 GEM Inputs for the Proposed 2027MY Class 7 and 8 Tractor Standard Setting
                                    Class 7
                                    Class 8
                                    Day Cab
                                    Day Cab
                                  Sleeper Cab
                                   Low Roof
                                   Mid Roof
                                   High Roof
                                   Low Roof
                                   Mid Roof
                                   High Roof
                                   Low Roof
                                   Mid Roof
                                   High Roof
                                    Engine
                           2027MY 11L Engine  350 HP
                           2027MY 11L Engine 350 HP
                           2027MY 11L Engine 350 HP
                           2027MY 15L Engine  455 HP
                           2027MY 15L Engine 455 HP
                           2027MY 15L Engine 455 HP
                           2027MY 15L Engine 455 HP
                           2027MY 15L Engine 455 HP
                           2027MY 15L Engine 455 HP
                          Aerodynamics (CdA in m[2])
                                     4.52
                                     5.92
                                     5.52
                                     4.52
                                     5.92
                                     5.52
                                     4.52
                                     5.92
                                     5.32
                      Steer Tires (CRR in kg/metric ton)
                                      5.6
                                      5.6
                                      5.6
                                      5.6
                                      5.6
                                      5.6
                                      5.6
                                      5.6
                                      5.6
                      Drive Tires (CRR in kg/metric ton)
                                      5.9
                                      5.9
                                      5.9
                                      5.9
                                      5.9
                                      5.9
                                      5.9
                                      5.9
                                      5.9
                Extended Idle Reduction Weighted Effectiveness
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                      3%
                                      3%
                                      3%
             Transmission = 10 speed Automated Manual Transmission
   Gear Ratios = 12.8, 9.25, 6.76, 4.90, 3.58, 2.61, 1.89, 1.38, 1.00, 0.73
                            Drive axle Ratio = 3.2
                        6x2 Axle Weighted Effectiveness
                                      N/A
                                      N/A
                                      N/A
                                     0.5%
                                     0.5%
                                     1.5%
                                     0.5%
                                     0.5%
	1.5%
                     Low Friction Axle Lubrication = 0.2%
                          Transmission benefit = 1.8%
                        Predictive Cruise Control =0.8%
                         Accessory Improvements = 0.3%
                Air Conditioner Efficiency Improvements = 0.2%
                    Automatic Tire Inflation Systems = 0.4%
                          Weight Reduction = 0 pounds
   Direct Drive Weighted Efficiency = 1% for sleeper cabs; 0.8% for day cabs

The proposed level of the 2027 model year standards, in addition to the phase-in standards in model years 2021 and 2024 for each subcategory is included in Table III-14.

Table III-14 Proposed 2021, 2024, and 2027 Model Year Tractor Standards
2021 Model Year CO2 Grams per Ton-Mile

Day Cab
Sleeper Cab

Class 7
Class 8
Class 8
Low Roof
97
78
70
Mid Roof
107
84
78
High Roof
109
86
77
2021 Model Year Gallons of Fuel per 1,000 Ton-Mile

Day Cab
Sleeper Cab

Class 7
Class 8
Class 8
Low Roof
9.5285
7.5639
6.8762
Mid Roof
10.5108
8.2515
7.6621
High Roof
10.7073
8.4479
7.5639
2024 Model Year CO2 Grams per Ton-Mile

Day Cab
Sleeper Cab

Class 7
Class 8
Class 8
Low Roof
90
72
64
Mid Roof
100
78
71
High Roof
101
79
70
2024 Model Year and Later Gallons of Fuel per 1,000 Ton-Mile

Day Cab
Sleeper Cab

Class 7
Class 8
Class 8
Low Roof
8.8409
7.0727
6.2868
Mid Roof
9.8232
7.5639
6.9745
High Roof
9.9214
7.7603
6.8762
2027 Model Year CO2 Grams per Ton-Mile

Day Cab
Sleeper Cab

Class 7
Class 8
Class 8
Low Roof
87
70
62
Mid Roof
96
76
69
High Roof
96
76
67
2027 Model Year and Later Gallons of Fuel per 1,000 Ton-Mile

Day Cab
Sleeper Cab

Class 7
Class 8
Class 8
Low Roof
8.5462
6.8762
6.0904
Mid Roof
9.4303
7.4656
6.7780
High Roof
9.4303
7.4656
6.5815

A summary of the draft technology package costs is included in Table III-15 through Table III-17 for MYs 2021, 2024, and 2027, respectively, with additional details available in the draft RIA Chapter 2.12.
Table III-15 Class 7 and 8 Tractor Technology Incremental Costs in the 2021 Model Year[a][,b]
Preferred Alternative vs. the Less Dynamic Baseline (2012$ per vehicle)

                                    Class 7
                                    Class 8

                                    Day Cab
                                    Day Cab
                                  Sleeper Cab

Low/Mid Roof
High Roof
Low/ Mid Roof
High Roof
Low Roof
Mid Roof
High Roof
Engine[c]
                                                                           $314
                                                                           $314
                                                                           $314
                                                                           $314
                                                                           $314
                                                                           $314
                                                                           $314
Aerodynamics
                                                                           $687
                                                                           $511
                                                                           $687
                                                                           $511
                                                                           $656
                                                                           $656
                                                                           $535
Tires
                                                                            $49
                                                                             $9
                                                                            $81
                                                                            $15
                                                                            $59
                                                                            $59
                                                                            $15
Tire inflation system
                                                                           $180
                                                                           $180
                                                                           $180
                                                                           $180
                                                                           $180
                                                                           $180
                                                                           $180
Transmission
                                                                         $3,969
                                                                         $3,969
                                                                         $3,969
                                                                         $3,969
                                                                         $3,969
                                                                         $3,969
                                                                         $3,969
Axle & axle lubes
                                                                            $50
                                                                            $50
                                                                            $70
                                                                            $90
                                                                            $70
                                                                            $70
                                                                            $90
Idle reduction with APU
                                                                             $0
                                                                             $0
                                                                             $0
                                                                             $0
                                                                         $2,449
                                                                         $2,449
                                                                         $2,449
Air conditioning
                                                                            $45
                                                                            $45
                                                                            $45
                                                                            $45
                                                                            $45
                                                                            $45
                                                                            $45
Other vehicle technologies
                                                                           $174
                                                                           $174
                                                                           $174
                                                                           $174
                                                                           $174
                                                                           $174
                                                                           $174
Total
                                                                         $5,468
                                                                         $5,252
                                                                         $5,520
                                                                         $5,298
                                                                         $7,916
                                                                         $7,916
                                                                         $7,771
Notes:
[a] Costs shown are for the 2021 model year and are incremental to the costs of a tractor meeting the phase 1 standards. These costs include indirect costs via markups along with learning impacts.  For a description of the markups and learning impacts considered in this analysis and how it impacts technology costs for other years, refer to Chapter 2 of the draft RIA (see draft RIA 2.12).
[b] Note that values in this table include adoption rates.  Therefore, the technology costs shown reflect the average cost expected for each of the indicated tractor classes.  To see the actual estimated technology costs exclusive of adoption rates, refer to Chapter 2 of the draft RIA (see draft RIA 2.12 in particular).
[c] Engine costs are for a heavy HD diesel engine meant for a combination tractor.

Table III-16 Class 7 and 8 Tractor Technology Incremental Costs in the 2024 Model Year[a][,b]
Preferred Alternative vs. the Less Dynamic Baseline (2012$ per vehicle)

                                    Class 7
                                    Class 8

                                    Day Cab
                                    Day Cab
                                  Sleeper Cab

Low/Mid Roof
High Roof
Low/ Mid Roof
High Roof
Low Roof
Mid Roof
High Roof
Engine[c]
                                                                           $904
                                                                           $904
                                                                           $904
                                                                           $904
                                                                           $904
                                                                           $904
                                                                           $904
Aerodynamics
                                                                           $744
                                                                           $684
                                                                           $744
                                                                           $684
                                                                           $712
                                                                           $712
                                                                           $723
Tires
                                                                            $47
                                                                            $11
                                                                            $78
                                                                            $18
                                                                            $58
                                                                            $58
                                                                            $18
Tire inflation system
                                                                           $330
                                                                           $330
                                                                           $330
                                                                           $330
                                                                           $330
                                                                           $330
                                                                           $330
Transmission
                                                                         $5,883
                                                                         $5,883
                                                                         $5,883
                                                                         $5,883
                                                                         $5,883
                                                                         $5,883
                                                                         $5,883
Axle & axle lubes
                                                                            $92
                                                                            $92
                                                                           $128
                                                                           $200
                                                                           $128
                                                                           $128
                                                                           $200
Idle reduction with APU
                                                                             $0
                                                                             $0
                                                                             $0
                                                                             $0
                                                                         $2,687
                                                                         $2,687
                                                                         $2,687
Air conditioning
                                                                            $82
                                                                            $82
                                                                            $82
                                                                            $82
                                                                            $82
                                                                            $82
                                                                            $82
Other vehicle technologies
                                                                           $318
                                                                           $318
                                                                           $318
                                                                           $318
                                                                           $318
                                                                           $318
                                                                           $318
Total
                                                                         $8,400
                                                                         $8,304
                                                                         $8,467
                                                                         $8,419
                                                                        $11,102
                                                                        $11,102
                                                                        $11,145
Notes:
[a] Costs shown are for the 2021 model year and are incremental to the costs of a tractor meeting the phase 1 standards. These costs include indirect costs via markups along with learning impacts.  For a description of the markups and learning impacts considered in this analysis and how it impacts technology costs for other years, refer to Chapter 2 of the draft RIA (see draft RIA 2.12).
[b] Note that values in this table include adoption rates.  Therefore, the technology costs shown reflect the average cost expected for each of the indicated tractor classes.  To see the actual estimated technology costs exclusive of adoption rates, refer to Chapter 2 of the draft RIA (see draft RIA 2.12).
[c] Engine costs are for a heavy HD diesel engine meant for a combination tractor.

Table III-17 Class 7 and 8 Tractor Technology Incremental Costs in the 2027 Model Year[a][,b]
Preferred Alternative vs. the Less Dynamic Baseline (2012$ per vehicle)

                                    Class 7
                                    Class 8

                                    Day Cab
                                    Day Cab
                                  Sleeper Cab

Low/Mid Roof
High Roof
Low/ Mid Roof
High Roof
Low Roof
Mid Roof
High Roof
Engine[c]
                                                                         $1,698
                                                                         $1,698
                                                                         $1,698
                                                                         $1,698
                                                                         $1,698
                                                                         $1,698
                                                                         $1,698
Aerodynamics
                                                                           $771
                                                                           $765
                                                                           $771
                                                                           $765
                                                                           $733
                                                                           $733
                                                                           $802
Tires
                                                                            $45
                                                                            $10
                                                                            $75
                                                                            $17
                                                                            $56
                                                                            $56
                                                                            $17
Tire inflation system
                                                                           $314
                                                                           $314
                                                                           $314
                                                                           $314
                                                                           $314
                                                                           $314
                                                                           $314
Transmission
                                                                         $6,797
                                                                         $6,797
                                                                         $6,797
                                                                         $6,797
                                                                         $6,797
                                                                         $6,797
                                                                         $6,797
Axle & axle lubes
                                                                            $97
                                                                            $97
                                                                           $131
                                                                           $200
                                                                           $131
                                                                           $131
                                                                           $200
Idle reduction with APU
                                                                             $0
                                                                             $0
                                                                             $0
                                                                             $0
                                                                         $2,596
                                                                         $2,596
                                                                         $2,596
Air conditioning
                                                                           $117
                                                                           $117
                                                                           $117
                                                                           $117
                                                                           $117
                                                                           $117
                                                                           $117
Other vehicle technologies
                                                                           $302
                                                                           $302
                                                                           $302
                                                                           $302
                                                                           $302
                                                                           $302
                                                                           $302
Total
                                                                        $10,140
                                                                        $10,099
                                                                        $10,204
                                                                        $10,209
                                                                        $12,744
                                                                        $12,744
                                                                        $12,842
Notes:
[a] Costs shown are for the 2021 model year and are incremental to the costs of a tractor meeting the phase 1 standards. These costs include indirect costs via markups along with learning impacts.  For a description of the markups and learning impacts considered in this analysis and how it impacts technology costs for other years, refer to Chapter 2 of the draft RIA (see draft RIA 2.12).
[b] Note that values in this table include adoption rates.  Therefore, the technology costs shown reflect the average cost expected for each of the indicated tractor classes.  To see the actual estimated technology costs exclusive of adoption rates, refer to Chapter 2 of the draft RIA (see draft RIA 2.12 in particular).
[c] Engine costs are for a heavy HD diesel engine meant for a combination tractor.
Proposed Heavy-Haul Tractor Standards
For Phase 2, the agencies propose to add a tenth subcategory to the tractor category for heavy-haul tractors.  The agencies recognize the need for manufacturers to build these types of vehicles for specific applications and believe the appropriate way to prevent penalizing these vehicles is to set separate standards recognizing a heavy-haul vehicle's unique needs, such as requiring a higher horsepower engine or different transmissions.  The agencies are proposing this change in Phase 2 because unlike in Phase 1 the engine, transmission, and drivetrain technologies are included in the technology packages used to determine the stringency of the proposed tractor standards and are included as manufacturer inputs in GEM.  This means that the agencies can adopt a standard reflecting individualized performance of these technologies in particular applications, in this case, heavy-haul tractors, and further, have a means of reliably assessing individualized performance of these technology at certification.
The typical tractor is designed with a Gross Combined Weight Rating (GCWR) of approximately 80,000 pounds due to the effective weight limit on the federal highway system, except in states with preexisting higher weight limits.  The agencies propose to consider tractors with a GCWR over 120,000 pounds as heavy-haul tractors.  Based on comments received during the development of HD Phase 1 (76 FR 57136-8), the agencies also believe it would be appropriate to further define the heavy-haul vehicle characteristics to differentiate these vehicles from the vehicles in the other nine tractor subcategories.  The two additional requirements would include a total gear reduction greater than or equal to 57:1 and a frame Resisting Bending Moment (RBM) greater than or equal to 2,000,000 in-lbs per rail or rail and liner combination.  Heavy-haul tractors typically require the large gear reduction to provide the torque necessary to start the vehicle moving.  These vehicles also typically require frame rails with extra strength to ensure the ability to haul heavy loads. We welcome comment on the proposed heavy-haul tractor specifications, including whether Gross Vehicle Weight Rating (GVWR) or Gross Axle Weight Rating (GAWR) would be a more appropriate metric to differentiate between a heavy-haul tractor and a typical tractor.
The agencies propose that heavy-haul tractors demonstrate compliance with the proposed standards using the day cab drive cycle weightings of 19 percent transient cycle, 17 percent 55 mph cycle, and 64 percent 65 mph cycle.  We also propose that GEM simulates the heavy-haul tractors with a payload of 43 tons and a total tractor, trailer, and payload weight of 118,500 pounds.  In addition, we propose that the engines installed in heavy-haul tractors meet the proposed tractor engine standards included in 40 CFR 1036.108.  We welcome comments on these proposed specifications.
The agencies recognize that certain technologies used to determine the stringency of the proposed Phase 2 tractor standards are less applicable to heavy-haul tractors.  Heavy-haul tractors are not typically used in the same manner as long-haul tractors with extended highway driving, and therefore would experience less benefit from aerodynamics.  Aerodynamic technologies are very effective at reducing the fuel consumption and GHG emissions of tractors, but only when traveling at highway speeds.  At lower speeds, the aerodynamic technologies may have a detrimental impact due to the potential of added weight.  The agencies therefore are not considering the use of aerodynamic technologies in the development of the proposed Phase 2 heavy-haul tractor standards.  Moreover, because aerodynamics would not play a role in the heavy-haul standards, the agencies propose to combine all of the heavy-haul tractor cab configurations (day and sleeper) and roof heights (low, mid, and high) into a single heavy-haul tractor subcategory.  We welcome comment on this approach.
Certain powertrain and drivetrain components are also impacted during the design of a heavy-haul tractor, including the transmission, axles, and the engine.  Heavy-haul tractors typically require transmissions with 13 or 18 speeds to provide the ratio spread to ensure that the tractor is able to start pulling the load from a stop.  Downsped powertrains are typically not an option for heavy-haul operations because these vehicles require more torque to move the vehicle because of the heavier load.  Finally, due to the loading requirements of the vehicle, it is not likely that a 6x2 axle configuration can be used in heavy-haul applications.
The agencies used the following heavy-haul tractor inputs for developing the proposed 2021, 2024, and 2027 MY standards, as shown in Table III-18 and Table III-19.
Table III-18 Application Rates for Proposed Heavy-Haul Tractor Standards
                     Heavy-Haul Tractor Application Rates

                                    2021MY
                                    2024MY
                                    2027MY
                                    Engine
                        2021 MY 15L Engine with 600 HP
                        2024 MY 15L Engine with 600 HP
                        2027 MY 15L Engine with 600 HP
                              Aerodynamics  -  0%
                                  Steer Tires
                                Phase 1 Baseline
                                      5%
                                      5%
                                      5%
                                    Level I
                                      60%
                                      50%
                                      20%
                                    Level 2
                                      25%
                                      30%
                                      50%
                                    Level 3
                                      10%
                                      15%
                                      25%
                                  Drive Tires
                               Phase 1 Baseline
                                      5%
                                      5%
                                      5%
                                    Level I
                                      60%
                                      50%
                                      20%
                                    Level 2
                                      25%
                                      30%
                                      50%
                                    Level 3
                                      10%
                                      15%
                                      25%
                                 Transmission
                                      AMT
                                      40%
                                      50%
                                      50%
                                   Automatic
                                      10%
                                      20%
                                      30%
                                      DCT
                                      5%
                                      10%
                                      10%
                              Other Technologies
                                   6x2 Axle
                                      0%
                                      0%
                                      0%
                         Low Friction Axle Lubrication
                                      20%
                                      40%
                                      40%
                           Predictive Cruise Control
                                      20%
                                      40%
                                      40%
                            Accessory Improvements
                                      10%
                                      20%
                                      30%
                    Air Conditioner Efficiency Improvements
                                      10%
                                      20%
                                      30%
                       Automatic Tire Inflation Systems
                                      20%
                                      40%
                                      40%
                               Weight Reduction
                                      0%

                                      0%
                                      0%

Table III-19 GEM Inputs for Proposed 2021, 2024 and 2027 MY Heavy-Haul Tractor Standards
                              Heavy-Haul Tractor
                                   Baseline
                                    2021MY
                                    2024MY
                                    2027MY
                    Engine = 2017 MY 15L Engine with 600 HP
                    Engine = 2021 MY 15L Engine with 600 HP
                    Engine = 2024 MY 15L Engine with 600 HP
                    Engine = 2027 MY 15L Engine with 600 HP
                       Aerodynamics (CdA in m[2]) = 5.00
                   Steer Tires (CRR in kg/metric ton) = 7.0
                   Steer Tires (CRR in kg/metric ton) = 6.2
                   Steer Tires (CRR in kg/metric ton) = 6.0
                   Steer Tires (CRR in kg/metric ton) = 5.8
                   Drive Tires (CRR in kg/metric ton) = 7.4
                   Drive Tires (CRR in kg/metric ton) = 6.6
                   Drive Tires (CRR in kg/metric ton) = 6.4
                   Drive Tires (CRR in kg/metric ton) = 6.2
                  Transmission = 13 speed Manual Transmission
Gear Ratios = 12.29, 8.51, 6.05, 4.38, 3.20, 2.29, 1.95, 1.62, 1.38, 1.17, 1.00, 0.86,  0.73
             Transmission = 13 speed Automated Manual Transmission
Gear Ratios = 12.29, 8.51, 6.05, 4.38, 3.20, 2.29, 1.95, 1.62, 1.38, 1.17, 1.00, 0.86,  0.73
             Transmission = 13 speed Automated Manual Transmission
Gear Ratios = 12.29, 8.51, 6.05, 4.38, 3.20, 2.29, 1.95, 1.62, 1.38, 1.17, 1.00, 0.86,  0.73
             Transmission = 13 speed Automated Manual Transmission
Gear Ratios = 12.29, 8.51, 6.05, 4.38, 3.20, 2.29, 1.95, 1.62, 1.38, 1.17, 1.00, 0.86,  0.73
                            Drive axle Ratio = 3.55
                            Drive axle Ratio = 3.55
                            Drive axle Ratio = 3.55
                            Drive axle Ratio = 3.55
                                      N/A
                     6x2 Axle Weighted Effectiveness = 0%
                     6x2 Axle Weighted Effectiveness = 0%
                     6x2 Axle Weighted Effectiveness = 0%
                                      N/A
                     Low Friction Axle Lubrication = 0.1%
                     Low Friction Axle Lubrication = 0.2%
                     Low Friction Axle Lubrication = 0.2%
                                      N/A
                              AMT benefit = 1.1%
                              AMT benefit = 1.8%
                              AMT benefit = 1.8%
                                      N/A
                        Predictive Cruise Control =0.4%
                        Predictive Cruise Control =0.8%
                        Predictive Cruise Control =0.8%
                                      N/A
                         Accessory Improvements = 0.1%
                         Accessory Improvements = 0.2%
                         Accessory Improvements = 0.3%
                                      N/A
                Air Conditioner Efficiency Improvements = 0.1%
                Air Conditioner Efficiency Improvements = 0.1%
                Air Conditioner Efficiency Improvements = 0.2%
                                      N/A
                    Automatic Tire Inflation Systems = 0.2%
                    Automatic Tire Inflation Systems = 0.4%
                    Automatic Tire Inflation Systems = 0.4%
                                      N/A
                          Weight Reduction = 0 pounds
                          Weight Reduction = 0 pounds
                          Weight Reduction = 0 pounds

The baseline 2017 MY heavy-haul tractor would emit 57 grams of CO2 per ton-mile and consume 5.6 gallons of fuel per 1,000 ton-mile.  The agencies propose the heavy-haul standards shown in Table III-20.  We welcome comment on the heavy-haul tractor technology path and standards proposed by the agencies.

Table III-20 Proposed Heavy-Haul Tractor Standards
                              Heavy-Haul Tractor

                                    2021 MY
                                    2024 MY
                                    2027 MY
                      Grams of CO2 per Ton-Mile Standard
                                      54
                                      52
                                      51
                      Gallons of Fuel per 1,000 Ton-Mile
                                    5.3045
                                    5.1081
                                     5.010
The technology costs associated with the proposed heavy-haul tractor standards are shown below in Table III-21.
Table III-21 Heavy-Haul Tractor Technology Incremental Costs in the 2021, 2024, and 2027 Model Year[a][,b]
Preferred Alternative vs. the Less Dynamic Baseline (2012$ per vehicle)

2021 MY
2024 MY
2027 MY
Engine[c]
                                                                           $314
                                                                           $904
                                                                         $1,698
Tires
                                                                            $81
                                                                            $78
                                                                            $75
Tire inflation system
                                                                           $180
                                                                           $330
                                                                           $314
Transmission
                                                                         $3,969
                                                                         $5,883
                                                                         $6,797
Axle & axle lubes
                                                                            $70
                                                                           $128
                                                                           $200
Air conditioning
                                                                            $45
                                                                            $82
                                                                           $117
Other vehicle technologies
                                                                           $174
                                                                           $318
                                                                           $302
Total
                                                                         $4,833
                                                                         $7,723
                                                                         $9,503
Notes:
[a] Costs shown are for the specified model year and are incremental to the costs of a tractor meeting the phase 1 standards. These costs include indirect costs via markups along with learning impacts.  For a description of the markups and learning impacts considered in this analysis and how it impacts technology costs for other years, refer to Chapter 2 of the draft RIA (see draft RIA 2.12).
[b] Note that values in this table include adoption rates.  Therefore, the technology costs shown reflect the average cost expected for each of the indicated tractor classes.  To see the actual estimated technology costs exclusive of adoption rates, refer to Chapter 2 of the draft RIA (see draft RIA 2.12 in particular).
[c] Engine costs are for a heavy HD diesel engine meant for a combination tractor.

    Consistency of the Proposed Tractor Standards with the Agencies' Legal Authority
The proposed HD Phase 2 standards are based on adoption rates for technologies that the agencies regard, subject to consideration of public comment,  as the maximum feasible for purposes of EISA Section 32902 (k) and appropriate under CAA Section 202 (a) for the reasons given in Section III.D.2(b) through (d) above; see also draft RIA Chapter 2.4.  The agencies believe these technologies can be adopted at the estimated rates for these standards within the lead time provided, as discussed in draft RIA Chapter 2.  The 2021 and 2024 MY standards are phase-in standards on the path to the 2027 MY standards and were developed using less aggressive application rates and therefore have lower technology package costs than the 2027 MY standards.  Moreover, we project the cost of these technologies would be rapidly recovered by operators due to the associated fuel savings, as shown in the payback analysis included in Section IX below.  The cost per tractor to meet the proposed 2027 MY standards is projected to range between $10,000 and $13,000 (much or all of this would be mitigated by the fuel savings during the first two years of ownership).  The agencies note that while the projected costs are significantly greater than the costs projected for Phase 1, we still consider that cost to be reasonable, especially given the relatively short payback period.  In this regard the agencies note that the estimated payback period for tractors of less than two years is itself shorter than the estimated payback period for light duty trucks in the 2017-2025 light duty greenhouse gas standards.  That period was slightly over three years, see 77 FR 62926-27, which EPA found to be a highly reasonable given the usual period of ownership of light trucks is typically five years.  The same is true here.  Ownership of new tractors is customarily four to six years, meaning that the greenhouse gas and fuel consumption technologies pay for themselves early on and the purchaser sees overall savings in succeeding years  -  while still owning the vehicle.  The agencies note further that the costs for each subcategory are relatively proportionate; that is, costs of any single tractor subcategory are not disproportionately higher (or lower) than any other.  Although the proposal is technology-forcing (especially with respect to aerodynamic and tire rolling resistance improvements), the agencies believe that manufacturers retain leeway to develop alternative compliance paths, increasing the likelihood of the standards' successful implementation.  The agencies also regard these reductions as cost-effective, even without considering payback period.  The agencies estimate the cost per metric ton of CO2eq reduction without considering fuel savings to be $20 in 2030, which compares favorably with the cost per ton of $142 per ton (in 2030) the agencies found to be reasonable for light duty trucks.  See 77 FR 62922.  The proposed phase-in 2021 and 2024 MY standards are less stringent and less costly than the proposed 2027 MY standards. For these reasons, and because the agencies have carefully considered lead time, EPA believes they are also reasonable under Section 202(a) of the CAA.  Given that the agencies believe the proposed standards are technically feasible, are highly cost effective, and highly cost effective  when accounting for the fuel savings, and have no apparent adverse potential impacts (e.g., there are no projected negative impacts on safety or vehicle utility), the proposed standards appear to represent a reasonable choice under Section 202(a) of the CAA and the maximum feasible under NHTSA's EISA authority at 49 U.S.C. 32902(k)(2).
Based on the information before the agencies, we currently believe that Alternative 3 would be maximum feasible and reasonable for the tractor segment for the model years in question.  The agencies believe Alternative 4 has potential to be the maximum feasible and reasonable alternative; however, based on the evidence currently before us, EPA and NHTSA have outstanding questions regarding relative risks and benefits of Alternative 4 due to the timeframe envisioned by the alternative.  Alternative 3 is generally designed to achieve the levels of fuel consumption and GHG reduction that Alternative 4 would achieve, but with several years of additional lead-time  -  i.e., the Alternative 3 standards would end up in the same place as the Alternative 4 standards, but several years later, meaning that manufacturers could, in theory, apply new technology at a more gradual pace and with greater flexibility.
    Alternative Tractor Standards Considered
The agencies developed and considered other alternative levels of stringency for the Phase 2 program.  The results of the analysis of these alternatives are discussed below in Section X of the preamble.  For tractors, the agencies developed the following alternatives as shown in Table III-22.
Table III-22 Summary of Alternatives Considered for the Proposed Rulemaking
Alternative 1
No action alternative
Alternative 2
Less Stringent than the Proposed Alternative applying off-the-shelf technologies
Alternative 3
(Proposed Alternative)
Proposed Alternative fully phased-in by 2027 MY
Alternative 4
Alternative that pulls ahead the proposed 2027 MY standards to 2024 MY
Alternative 5
Alternative based on very high market adoption of advanced technologies
When evaluating the alternatives, it is necessary to evaluate the impact of a proposed regulation in terms of CO2 emission reductions, fuel consumption reductions, and technology costs.  However, it is also necessary to consider other aspects, such as manufacturers' research and development resources, the impact on purchase price, and the impact on purchasers.  Manufacturers are limited in their ability to develop and implement new technologies due to their human resources and budget constraints.  This has a direct impact on the amount of lead time that is required to meet any new standards.  From the owner/operator perspective, heavy-duty vehicles are a capital investment for firms and individuals so large increases in the upfront cost could impact buying patterns.  Though the dollar value of the lifetime fuel savings will far exceed the upfront technology costs, purchasers often discount future fuel savings for a number of reasons.  The purchaser often has uncertainty in the amount of fuel savings that can be expected for their specific operation due to the diversity of the heavy-duty tractor market.  Although a nationwide perspective that averages out this uncertainty is appropriate for rulemaking analysis, individual operators must consider their potentially narrow operation. In addition, purchasers often put a premium on reliability (because downtime is costly in terms of towing, repair, late deliveries, and lost revenue) and may perceive any new technology as a potential risk with respect to reliability.  Another factor that purchasers consider is the impact of a new technology on the resale market, which can also be impacted by uncertainty.
The agencies selected the proposed standards over the more stringent alternatives based on consideringthe relevant statutory factors. In 2027, the proposed standards achieve up to a 24 percent reduction in CO2 emissions and fuel consumption compared to a Phase 1 tractor at a per vehicle cost of approximately $13,000.  Alternative 4 achieves the same percent reduction in CO2 emissions and fuel consumption compared to a Phase 1 tractor, but three years earlier, at a per vehicle cost of approximately $14,000.  The alternative standards are projected to result in more emission and fuel consumption reductions from the heavy-duty tractors built in model years 2021 through 2026.  We project the proposed standards to be achievable within known design cycles, and we believe these standards would allow different paths to compliance in addition to the one we outline and cost here.
The agencies solicit comment on all of these issues and again note the possibility of adopting, in a final action, standards that are more accelerated than those proposed in Alternative 3. The agencies are also assuming that both the proposed standards and Alternative 4 could be accomplished with all changes being made during manufacturers' normal product design cycles.  However, we note that doing so would be more challenging for Alternative 4 and may require accelerated research and development outside of design cycles with attendant increased costs.
The agencies are especially interested in seeking detailed comments on Alternative 4.  Therefore, we are including the details of the Alternative 4 analysis below.  The adoption rates considered for the 2021 and 2024 MY standards developed for Alternative 4 are shown below in Table III-23 and Table III-24.  The inputs to GEM used to develop the Alternative 4 CO2 and fuel consumption standards are shown below in
Table III-25 and Table III-26.  The standards associated with Alternative 4 are shown below in Table III-27.  Commenters are encouraged to address all aspects of feasibility analysis, including costs, the likelihood of developing the technology to achieve sufficient relaibility within the proposed lead time, and the extent to which the market could utilize the technology.
    Derivation of Alternative 4 Tractor Standards
The adoption rates considered for the 2021 and 2024 MY standards developed for Alternative 4 are shown below in Table III-23 and Table III-24.  The inputs to GEM used to develop the Alternative 4 CO2 and fuel consumption standards are shown below in
Table III-25 and Table III-26.  The standards associated with Alternative 4 are shown below in Table III-27.  Commenters are encouraged to address all aspects of feasibility analysis, including costs, the likelihood of developing the technology to achieve sufficient relaibility within the lead time.

Table III-23 Alternative 4 Adoption Rates for 2021 MY

                                    Class 7
                                    Class 8

                                    Day Cab
                                    Day Cab
                                  Sleeper Cab

                                   Low Roof
                                   Mid Roof
                                   High Roof
                                   Low Roof
                                   Mid Roof
                                   High Roof
                                   Low Roof
                                   Mid Roof
                                   High Roof
                Alternative 4 2021MY Engine Technology Package

                                     100%
                                     100%
                                     100%
                                     100%
                                     100%
                                     100%
                                     100%
                                     100%
                                     100%
                                 Aerodynamics
                                     Bin I
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                      0%
                                    Bin II
                                      65%
                                      65%
                                      0%
                                      65%
                                      65%
                                      0%
                                      65%
                                      65%
                                      0%
                                    Bin III
                                      30%
                                      30%
                                      35%
                                      30%
                                      30%
                                      35%
                                      30%
                                      30%
                                      35%
                                    Bin IV
                                      5%
                                      5%
                                      30%
                                      5%