,dCEEE:: 

Amer.can Counetl fur an [r,crgy EfftL•r~rll Ecvnonw 529 14th Srreel rl W Surtc 600 <!' Washrnglon. O.C 20045 o 202 5074000 o 202 429 2248 '·' www.aceee.org 

Comments on EPA' s and NHTSA's Proposed Greenhouse Gas Emissions and Fuel 

Efficiency Standards for Medium- and Heavy-Duty Engines and VehiclesPhase 2 

Siddiq Khan, American Council for an Energy-Efficient Economy (ACEEE) 

Chicago, ll Hearing-August 6, 2015 

My name is Siddiq Khan, and I am a senior transportation researcher and the heavy-duty 

vehicle lead at the American Council for an Energy-Efficient Economy (ACEEE). ACEEE, founded 

in 1980, is a nonprofit organization that acts as a catalyst for energy efficiency policies, 

programs, technologies, investments, and behavior. 

The adoption of the first-ever greenhouse gas emissions and fuel efficiency standards for 

heavy-duty vehicles and engines in 2011 was a historic step in reducing emissions and oil 

consumption from the transportation sector. The proposed Phase 2 standards, built on the 

success of the Phase 1 program, would provide substantial gains in fuel efficiency for heavyduty vehicles by 2027, provide continuity and certainty to the manufacturers, deliver savings at 

the pump to truck owners and operators, and reduce freight costs. The heavy-duty fuel 

efficiency program is also a key element of the president's climate action plan. 

ACEEE applauds the agencies' excellent work in developing the Phase 2 standards. The 

proposed rule improves upon the existing Phase 1 program in several ways, including: 

• Full vehicle integration. The modeling tool used to calculate vehicles' fuel efficiency 

{GEM) will become more sophisticated, which will allow many more technologies to 

contribute to certified fuel efficiency. For example, transmission improvements will 

register in the vehicle certification process for the first time. The vehicle certification 

protocols will promote integration of engine, transmission, and vehicle components. 

ACEEE strongly supports the agencies' proposal that tractor and vocational vehicle 

manufacturers be required to chassis test a small number of vehicles each year in order 

to help detect any inconsistencies between emissions reductions simulated in GEM and 

reductions realized in vehicle operation 

• Inclusion of trailers. This is crucial, because known, affordable trailer aero and tire 

technologies can deliver over 10% fuel savings for tractor-trailers. 

• Vocational vehicle segmentation and re-weighting of test cycles. The addition of 

vocational vehicle classes will better reflect vehicles' operating characteristics. Test 

cycles will match vehicles' real-world duty cycles much better than they do in the Phase 

1 program, especially in the case of vocational vehicles, for which an idle cycle has been 

added. Inclusion of road grade on the 55- and 65-mph steady-state cycles in Phase 2 will 

better reflect real-world driving. Reweighting operating points for tractor truck engine 

certification based on real-world data is another positive step. 

Yet, the proposal can and should be strengthened in several areas to capture more of the 

available fuel savings and promote greater adoption of advanced technologies. 

• The standards for diesel engines in tractor applications should be strengthened to 

provide a strong incentive for manufacturers to make major, sustained investment in 

engine efficiency technologies over the next 15 years. The proposed 4% improvement in 

engine efficiency over a decade falls far short of what can be achieved and should be 

increased to at least 10%. 

• Gasoline engine efficiency, which would remain unchanged under the proposal, should 

continue to improve, in order to deliver greater fuel savings and avoid upsetting the 

gasoline/diesel balance of vocational vehicles. 

• Fuel efficiency requirements for heavy-duty gasoline pickups and vans should be more 

consistent with standards for their light-duty counterparts. As proposed, the weightadjusted fuel economy target for a Ford F-250 heavy-duty pickup truck in MY 2025 is 

33% lower than the target for a Ford F-150 light-duty truck with similar engine, 

transmission, and power specs. Such a large discrepancy in fuel efficiency targets for 

light- and heavy-duty pickups could result in market distortions and cost heavy pickup 

owners money at the pump. 

• Consumer fuel efficiency labels, similar to those for cars and light trucks, should be 

required for heavy-duty pickup trucks and vans. 

• The Phase 2 standards proposed for 2027 can and should be moved forward to 2024. 

Most of the fuel-saving technologies needed for Phase 2 compliance are available in the 

market today, and the remainder will be available within the next few years. 

To conclude, ACEEE strongly supports EPA and NHTSA's Phase 2 greenhouse gas and fuel 

efficiency standards for heavy-duty vehicles and engines. The proposed rule, built on the 

success of the first phase, represents another important step in the right direction toward 

managing fuel consumption and greenhouse gas emissions of the heavy-duty sector. We 

recommend that the agencies strengthen the proposed rule in several areas to ensure that the 

Phase 2 program achieves maximum economic and environmental benefits. 

TRB Paper 15-4977 

Fuel Savings Available in New Heavy-Duty Trucks in 2025 

Siddiq Khan, Ph.D. 1

, 

American Council for an Energy-Efficient Economy (ACEEE) 

529 141

h Street, N.W., Washington, DC 20045 

1 Corresponding Author 

Phone: (202) 507-4019 

Fax: (202) 429-2248 

Email: skhan@aceee.org 

Dave Cooke, Ph.D., 

Union ofConcemed Scientists (UCS) 

1825 K Street, NW 8th floor 

Washington, DC 20006 

Phone: (202) 331-6948 

Email: dcooke@ucsusa.org 

Luke Tonachel 

Natural Resources Defense Council (NRDC) 

40 West 20th Street 

New York, NY 10011 

Phone: (212) 727-4607 

Email: ltonachel@nrdc.org, 

Submitted Nov 14, 2014 

Word Count: 4,778 

Table Count: 07 

Figure Count: 02 

Equivalent Words: 7,028 
ABSTRACT 

In 20 I l, the Environmental Protection Agency (EPA) and the National Highway Traffic 

Safety Administration (NHTSA) adopted the first-ever fuel efficiency and greenhouse gas 

emissions standards for medium- and heavy-duty vehicles and engines built for the 2014 to 2018 

model years. Those standards will benefit truckers and consumers and save over a half-million 

barrels of oil per day by 2030. The EPA and NHTSA are now working to extend this program 

beyond 2018. Large opportunities are now available to increase the fuel efficiency of heavy-duty 

vehicles beyond the technologies needed to meet the 2014 to 2018 standards. We evaluate fuelsaving technologies now available or under development for these vehicles, their engines and 

transmissions. Our analysis shows that, by 2025, these technologies could contribute to achieve a 

reduction of at least 40 percent in average new truck fuel consumption from its 2010 levels or by 

30 percent beyond the 2011 rule targets. This reduction would yield oil savings of 1.4 million 

barrels of oil per day in 2030. These technologies are also cost-effective. The payback period for 

some more specialized truck types will be longer, but average payback will be under two years. 

Keywords: Heavy-duty vehicles, Fuel efficiency and GHG rule, Emerging Technologies 

INTRODUCTION 

The heavy-duty on-road vehicles include vehicles with minimum gross vehicle weight 

rating (GVWR) of 8,500 lbs. to freight trucks with 80,000 lbs. or more GVWR. Three major 

groups of vehicles represent the heavy-duty sector: Class 2b/3 pickups and vans, Class 3-8 

vocational vehicles including refuse and delivery trucks and transit buses, and tractor trucks that 

are engaged in long and short haul freight movements. In 2013, U.S. highway vehicles consumed 

2 1.5 quadrill ion British thermal units (Btus) of energy, or about 11.3 million barrels of oil per 

day (MBD) (EIA 2014), 28 percent of which was consumed by heavy-duty vehicles. Heavy-duty 

vehicle energy use is dominated by large tractor trucks (Class 7 and 8) engaged in moving freight 

across the country, consuming 66 percent of heavy-duty energy, 17 percent of total 

transportation energy and 12 percent of all U.S. oil consumption (EPA 2011 ). 

THE 2011 FUEL EFFICIENCY AND GHG EMISSIONS RULE 

The EPA and NHTSA (called 'the agencies' hereafter) adopted the first-ever fuel 

efficiency and greenhouse gas emissions standards (EPA and NHTSA 201 1 a) for these vehicles 

in 2011 (termed 'Phase 1' hereafter). The rule covers three major categories of conm1ercial 

vehicles: heavy-duty pickup trucks and vans (Class 2b and 3); vocational vehicles (Class 2b-8); 

and tractor trucks (Class 7 and 8). It also covers engines used in heavy-duty vocational and 

tractor trucks. Engine and vehicle manufacturers are the parties to be regulated. Trailers used 

with tractor trucks are not included. 

The agencies set standards for C02 emissions and fuel efficiency and also established 

emission caps for methane (CH4) and nitrous oxide (N20). The EPA program to reduce C02 

emissions begins with model year (MY) 2014 vehicles, while the NHTSA's fuel efficiency 

program is voluntary for 20 14 and 2015 vehicles and becomes mandatory in MY 2016. The 

Phase 1 standards adopted by both agencies extend to model year 2018 and then remain in effect 

2 
unless amended by future rulemakings, such as the post-20 18 "Phase 2" standards (EPA and 

N IITSA 201la). 

Overall, the Phase I standards require about a 16 percent reduction in fuel consumption, 

on average, from all heavy-duty vehicles. The rule has two-step improvements: the first in MY 

2014 and the second in MY 2017. It requires the greatest fuel consumption reduction from 

tractor trucks, ranging from 7 to 22 percent in 20 14-2016 and from 10 to 24 percent in 2017. 

compared to the 20 I 0 level. The range of improvements depends on the physical specifications 

of tractor trucks, including roof height and cab type, which affect the efficacy of aerodynan1ic 

improvements and anti-idle devices. Vocational vehicles will reduce fuel consumption by 4 to 5 

percent in 20 14-2016 and by 6 to 9 percent in 20 17 from the 20 I 0 level. These reductions 

include the required improvements in engine fuel efficiency. Heavy-duty commercial pickups 

and vans will reduce fuel consumption by 11 percent for gasoline fueled trucks and by 16 percent 

for diesel fueled trucks by 2018 from a combined 2010 gasoline/diesel baseline. Manufacturers 

must meet the standards not on a vehicle-by-vehicle basis but on average over vehicles sold in 

each class. These reductions can be achieved using readily available, "off-the-shelf'' 

technologies. EPA and NHTSA estimated that the combined standards would reduce C02 

emissions by about 270 million metric tons and save about 530 million barrels of oil over the life 

of model year 2014 to 20 18 vehicles (EPA 20 I I). 

The Phase I rule can be improved in several ways. The stringency of the rule was set 

based on the assessed capability of individual components. An improved approach would 

consider the way all components work together in a full vehicle configuration. For example, the 

Phase I rule failed to consider any transmission improvements and their potential optimization 

with the engine and reduced vehicle load. Further, by not regulating trailers for tractors, the 

Phase 1 rule missed large fuel saving opportunities. 

HEAVY-DUTY VEHICLE PHASE 2 RULEMAKING 

The agencies are now working on the next phase of the heavy-duty vehicle rule (White 

House 2014). While the Phase 1 regulation re lied entire ly on off-the-shelf technologies that were 

immediately ready to deploy, as indicated by the high levels of early certification from engine 

manufactmers, many of the technologies that are applicable by 2025 are still in the 

demonstration phase. However, manufacturers have indicated that technologies such as waste 

heat recovery, advanced aerodynamics, and transmission technologies which have been used in 

advanced vehicle demonstrations such as the Department of Energy's SuperTruck program 

(Howden 20 14), could be brought into the market over the next 5 to I 0 years. These 

technologies have been identified in analyses such as the National Research Council Panel repo11 

as applicable in the 2020 timeframe (NRC 20 I 0), and the next phase of standards can help 

encourage their widespread deployment. 

VEHICLE POPULATIONS AND CHARACTERISTICS 

To mirror the agencies· process, we have assumed 20 10 model year base line vehicles for 

a ll classes of vehicles. We have also grouped the vehicles into the three broad categories 

identified in the Phase I program: Class 7-8 tractor-trailers, Class 2b-8 vocational vehicles, and 

Class 2b-3 pick-ups and vans. Class7-8 tractor trailers are the biggest fue l users, consuming 

3 
about two-thirds of total heavy-duty fuel consumption, fo llowed by vocational vehicles and 

pickups and vans, consuming 22% and 12%, respectively (EPA and NHTSA 20l lb). However, 

because certain technologies may be more or less effective under different operational 

conditions. applicable to only certain fuels, or economically viable only in certain applications. 

we further sub-categorized these vehicles as appropriate to better quantify the real technological 

potential for reducing fuel consumption from medium- and heavy-duty vehicl es. 

Tractor-Trailers 

In the Phase 1 program, tractor-trailers are divided into nine categories defined by 

GYWR (Class 7 or 8), operation (regional or long-haul), and cab height (low-, medium-, or highroof cab) as shown in Table I. In our work, we have consolidated these nine categories into 

three: day cabs (shown in yellow in Table I), low-roof sleeper cabs (blue), and high-roof sleeper 

cabs (green). This consolidation was deemed adequate to capture differences in both duty cycle 

(regional operation of day cabs compared to long-haul operation of sleeper cabs) and trailers 

being pulled (low- and medium-roof tractors tend to pull non-van trailers such as flatbeds and 

tankers. while high-roof tractors will pull almost exclusively box, or van, trailers) while 

minimizing redundancy in the discussion of technology application and effectiveness. 

TABLE 1. Assumed sales fractions of tractor trailers and consolidation of classes (Source: 

EPAINHTSA 2011b). 

Class 7 (GVWR from 26,001 8 (GYWR greater than 33,000 lbs.) 

to 33,000 lbs.) 

Cab Style Day Sleeper 

Roof Low Med High Low Med High Low Med High 

Sales Fraction 4% 0% 4% 18% 0% 14% 3% 9% 48% 

Note· Day cabs arc shown in yellow. Low-roof sleeper cabs are shown in blue H•gh-roofsleepcr cabs arc shown in green. 

To determine the relative populations of these vehicles, we relied upon the new vehicle 

sales projected in the agencies' mlemaking for the 20 18 model year (EPA and NHTSA 2011 b). 

Baseline fuel economy was also taken directly from the agencies' work. However, for the 

annua l vehicle miles traveled, we found that whi le the agencies' appraisal of long-haul tractor 

trailer operation was appropriate (EPA and NHTSA 2011 b), it did not account for the lower 

annual vehicle miles traveled (VMT) that would occur during regional operation. Therefore. for 

day cabs, we derived the annual vehicle mileage through the Vehicle Inventory and Use Survey 

(VIUS), taking the average annual mileage for tractors with a primary range of operation of less 

than 200 miles. (VIUS 2002). 

4 
Vocational Vehicles 

Vocational vehicles encompass a wide assortment of vehicles within many different 

weight classes, body types, and operational cycles. In the agencies' fuel economy and 

greenhouse gas standards, vocational vehicles are separated into three classes, by weight: light 

heavy-duty (Class 2b-5), medium heavy-duty (Class 6-7), and heavy heavy-duty (Class 8). 

Because these categories do not sufficiently de fine a duty cycle or narrow the applicable 

technologies in any way, we have ignored weight as a determining factor in our analysis. 

However, we do believe that certain technologies are only applicable under certain duty cycles. 

Therefore. we have sub-divided vocational vehicles into two primary groups based on the 

applicability of hybrid technologies, which are appropriate primarily for start-stop duty cycles. 

Though the agencies have considered buses in the ir assessment of vocational vehicles, we do not 

separately consider that operation because it is a small population of very specialized vehicles. 

Current hybrid architectures have been demonstrated primarily in four types of vehicles: 

refuse trucks. urban delivery trucks, utility (or bucket) tmcks, and transit buses (TIAX 2009). 

Because we have not separately considered transit buses in our analysis, we have focused on the 

delivery, refuse, and uti lity trucks in determining our segmentation. According to VIUS 2002, 

refuse trucks and utility trucks each represented approximately 5 percent of the total Class 2b-8 

vocational fleet. Step vans, beverage trucks, insulated refrigerated vans, and other van-type 

trucks represented more than one quarter of Class 2b-8 vocational vehicles. Because this 

population of vehicles includes a range of duty cycles, from urban stop-and-go to rural/highway 

hauling, we consider that only halfofthese vehic les would have a duty cycle appropriate to 

hybrids. This leads to an approximate division of vocational vehicles into 5 percent refuse, 5 

percent bucket, 15 percent urban delivery, and 75 percent other. This is likely an underestimate 

of the number of vehic les for which hybridi zation could be applicable, as a survey of California 

vocational vehicles found that more than halfofthe Class 3-8 vocational vehicles ran under 

urban or work-site duty cycles, as opposed to rural or intercity operation (Call lEA T 20 13). 

The agencies identified a baseline fuel economy for the entire vocational fl eet of9.7 mpg 

(EPA and NHTSA 2011 b). Our ana lysis of the efficiency of the 25 percent of vehic les where 

hybrids would be appropriate led to an average of 6.0 mpg (TIAX 2009), leaving the remaining 

75 percent with a baseline fuel economy of 12.2 mpg. We assumed 22,087 annual miles for all 

vocational vehicles that we calculated from VIUS 2002. Our analysis ofVMT across all types of 

vocational vehicles indicated that their annual VMT varied by vehicle type but in our analysis we 

assumed a single average figure. Our figure is within the range identified in other reports (NRC 

2010, EPA and NHTSA 201 1 b). 

Pick-ups and Vans 

For Class 2b-3 pick-ups and vans, the Phase 1 rule set different standards for diesel and 

gasoline vehicles. In our analysis, we retain that distinction because the engine technologies 

applicable and their effectiveness will be very different for the two powertrains. 

As for the other classes, we determined the total number of pick-ups using the agencies 

projected sales for the 2018 model year (EPA and NHTSA 20 It b). The fraction of diesel versus 

gasoline pick-ups was detem1ined using the projections from the Energy Information 

5 
Administration (EIA 20 14). Baseline efficiencies were taken from the agencies' analysis (EPA 

and NHTSA 201 1 b), accounting for a 20 percent shortfall typical of the difference between the 

light-duty combined city/highway test cycle and real world fuel economy. Annual VMT was 

taken to be the same for all pick-ups and vans, using the average VMT in VIUS 2002 for Class 

2b-3 pick-ups and vans. 

ENGINE AND VEHICLE TECHNOLOGY ASSUMPTIONS 

The primary resources used to estimate technology cost and performance were EPA and 

NHTSA ·s Phase l Final Regulatory Impact Analysis (EPA and NHTSA 20 11 b) and Final Rule 

(EPA and NHTSA 201 l a), the National Research Councirs technology assessment report (NRC 

20 I 0), the technology assessment carried out by TIAX LLC (TIAX 2009) in support of the NRC 

report and the DOE Super Truck program (Howden 2014). In a few cases, we used industry 

sources (Cummins 2013, DTNA 2013, Eaton 2013), as noted below. 

While estimating the overall fuel consumption reduction from individual technologies, 

we followed the NRC study approach. The NRC Study calculated the percent fuel consumption 

reduction (% FCR) from packages of efficiency technologies as follows: 

% FCRpackage = 100 [1 - (1 - {% FCRtechl/100 }) ( I - {% FCRtech21100}) .. . {(I -

{% FCRtechN/100} )] 

where % FCRtechx is the percent benefit of an individual technology. 

This approach is, however, conservative since benefits from some of the technologies 

may be additive. 

Jn considering whether a technology is applicable to a particular vehicle class, it is 

important to consider whether the technology is economically viable as well as technologically 

feasible. Therefore, for each technology package, we examined the payback of the package using 

a discount rate of 5 percent, which falls between the standard discount rates of 3 percent and 7 

percent used by the Office of Management and Budget (OMB 1992). Fuel prices were assumed 

to be the 2020 projections for diesel and gasoline given in Annual Energy Outlook 2013 (EIA 

2013)·. Technology costs were given in many of the same sources as the values for effectiveness. 

All technology packages included achievable payback well within the lifetime mileage of the 

vehicle. 

Tractor Trailer Engine and Vehicles 

We assume that engines for tractor trucks will be equipped with waste heat recovery 

(bottoming cycle). Engines will be downsized to I 1 liters from 14 liters and will operate at II 00-

1300 rpm compared to present operation at 1400- 1600 rpm. Other engine improvements will 

include better air handling and exhaust gas recirculation, dual-stage turbocharging, combustion 

optimi zati on and improvements in selective catalytic reduction (SCR), as shown in Table 2. We 

omitted some technologies considered by the NRC panel in order to avoid double-counting 

benefits already counted for the included technologies. Note that we provide the minimum and 

maximum fuel consumption reduction potential for individual technologies which reflect the 

variation in fuel savings across vehicle types within the class. 

6 
TABLE 2 Engine Technologies for Tractor Trailers 

% Fuel Consumption Reduction 

Technology 

Dual-stage turbocharging <al 

Improved combustion <b> 

Engine friction reduction (b) 

Reduced parasitic loads (accessories) (bl 

Aftertreatment improvement (bJ 

Engine downsizing+ downspeeding <c> 

Bottoming cycle <dJ 

Totab· 

Min Max 

2.5% 5.0% 

1.0% 3.0% 

0.5% 2.0% 

2.0% 4.0% 

1.0% 2.0% 

4.0% 4.0% 

6.0% 8.0% 

15.9% 25.0% 

Sources: (a) NRC 2010. (b) EPNNHTSA 20 1 lb: (c) DTNA 2013. (d) TIAX 2009 

Estimates of fue l consumption reductio n opportunities for high-roof sleeper cab tractor 

trucks are shov,rn in Table 3a. These improvements yield a reduction in fuel consumption of 42-

50 percent from 20 I 0 levels, or 23 to 34 percent from 2017 (Post Phase I) levels. Here, the 

applied technologies arc lightweight aluminum wheels on the tractor, aerodynamic skirts for 

non-box trailers, a full aerodynamic package including boat tail and gap reducer for box trail ers, 

low-rolling resistance (LRR) tires on the tractor and trailer, an advanced automated manual 

transmission, and idle reduction for sleeper cabs. Some of the technologies shown wilJ be 

employed by manufacturers to achieve the Phase I standards; these techno logies will not 

contri bute to the estimate of savings beyond 20 17. Tractor trailers other tha n those with highroof sleeper cabs have similar opportunities for engines and transmissions and fewer reduction 

opportunities elsewhere, a finding which re flects a different duty cycle for these vehicles. We 

calculate that fuel consumption of low- and mid-roof sleeper cabs can be reduced by 38 to 4 7 

percent relative to 20 I 0 (Table 3b ). Fuel consumption of day cab tractor trucks can be reduced 

by 35 to 42 percent from 20 I 0 level or by 2 1 to 33 percent from 2017 levels (Table 3c). 

ln order to estimate savings potentia l from tractor-trailers as a whole, we multiplied the 

fue l savings potentia l of high-, mid-, and low roof sleeper cabs by their respecti ve market shares. 

TABLE 3a Technology Package for High Roof Sleeper Cab Tractor Trucks 

% Fuel Consumption Reduction 

Technology 

Engine improvement <a> 

Transmission (b) 

Tractor Aerodynamics (b) 

Tra iler Aerodynamics (x 3) (b) 

LRR Tires (including trailer x 3) <b> 

Aluminum wheels (tractor) (c) 

Idle Reduction (b) 

Totals 

7 

Min Max 

15 .9% 25.0% 

7.0% 7.0% 

3.0% 4.0% 

8.3% 8.3% 

11.0% 11.0% 

1.0% 1.0% 

5.0% 8.0% 

41.8% 50.2% 
(a) Table 1: (b) NRC 2010. (c) EPAINHTSA 2011b 

TABLE 3b Technology Package for Low!Mid Roof Sleeper Cab T ractor Trucks 

% Fuel Consumption Reduction 

Technology 

Engine improvement (a) 

Transmission (b) 

Tractor Aerodynamics (b) 

Trailer Aerodynamics (x 3) (b) 

LRR Tires (including trailer x 3) tbl 

Aluminum wheels (tractor) (c) 

Idle Reduction (b) 

Totals 

(a) Table 1: (b) NRC 2010. (c) EPAINIITSA 201 1b 

Min Max 

15.9% 25.0% 

7.0% 7.0% 

2.0% 2.0% 

3.5% 3.5% 

11.0% 11.0% 

1.0% 1.0% 

5.0% 8.0% 

38.1% 46.5% 

TABLE 3c Technology Package fo r Day Cab Tractor T rucks 

% Fuel Consumption Reduction 

Technology 

Engine improvement (a) 

Transmission <b> 

Tractor Aerodynamics (b) 

Trailer Aerodynamics (x 3) (b) 

LRR Tires (includi ng trailer x 3) <bl 

Aluminum wheels (tractor) (c) 

Totals 

(a) Table 1: (b) NRC 20 10: (c) EPAINHTSA 2011 b 

Min Max 

15.9% 25.0% 

7.0% 7.0% 

2.0% 2.0% 

3.6% 3.6% 

11.0% 11.0% 

1.0% 1.0% 

34.9% 41.9% 

In addition to the technologies identified above, further technology advances are 

anticipated for tractor trailers in the Phase 2 timeframe, though they may not be employed fully 

across the fleet. These improvements include more advanced trailer aerodynamic packages 

(NRC 201 0), dual-clutch automated manual transmissions (Eaton 20 13), 6 x 2 drive axles 

(NACFE 20 14), vehicle speed limiters (EPA and NHTSA 2010b), Eco transmissions (i.e. 

transmission gear at neutral while cru ising at downhill), and both long-haul (TIAX 2009) and 

short-haul (NREL 20 12) hybridization. We have assumed in our final results (Table 5) 

additional improvements from these technologies of 5.5% or higher for high-roof sleeper cabs 

and 1.4% or more for both low-roof sleeper cabs and day cabs, well below the levels of 

improvement that would be achieved with widespread application ofthese technologies. 

8 
Vocational Vehicle Engine and Vehicles 

TABLE 4 Technology Package for Vocational Vehicles 

% Fuel Consumption Reduction 

Technology 

Improved combustion (a) 

Turbochargers improvement (a) 

Efficiency in air-handling (a) 

Low-temp exhaust gas recirculation (a) 

Engine friction reduction (a) 

Electrification of accessories <a) 

Hybridization (b) 

Transmission (c) 

Tires and wheels (b) 

Cab aerodynamics (dJ 

Totalst 

(a) EPAINIITSA 2010b. (h) 1\'RC 2010. (c) Eaton 2013: (dl TIAX 2009 

Min Max 

1.0% 3.0% 

1.0% 2.0% 

1.0% 1.0% 

1.0% 2.0% 

1.0% 2.0% 

2.0% 4.0% 

30.0% 40.0% 

8.0% 10.0% 

2.0% 4.0% 

5.0% 8.0% 

22.8% 33.2% 

t Includes 25°o pcnctmt1on ofhybnds and 10•• penetration of cab acro<:l) namics 

Technology estimates for vocational vehicles are presented in Table 4. For vocationa l 

vehicles, we considered only diesel engines for simplicity. However, as noted in the pick-up 

truck section below, gasoline engines would likely result in similar levels of improvement. We 

have largely considered a similar suite of technologies for the vocational diesel engines that we 

did for the tractor-trailers; however, because the duty cycles are more diverse and result in 

significantly more transient operation. waste heat recovery was not considered for vocational 

vehicles. 

The single biggest potential area of reduction in fuel consumption comes from the 

adoption of parallel hybrid powertrains in utility trucks, refuse trucks, and box trucks. As 

described above, this technology is only applicable to those vehicles with the most start-stop 

intense duty cycles and was therefore applied to just 25 percent of the vocational fleet. 

Similarly, aerodynamic improvements would only result in substantial fuel savings for those 

vehicles that travel predominantly at high speeds and were therefore only applied to 10 percent 

ofthe Oeet. 

Heavy-Duty Picku p Tr ucks and Vans 

Our analysis focused on complete pickups and vans, which constitute more than 90 

percent of Class 2b-3 vehicles, according to the Phase I rule (EPA and NHTSA 20 1la). The 

incomplete pickups are e ither without the primary load carrying device or no container being 

attached (EPA and NI-ITSA 20 11 a). The majority of the improvement projected for these 

vehicles will come from e ngine and transmission and accessory electrification. These fuel 

consumption reduction estimates are based on turbocharging and downsizing for gasoline 

engines and 42V start-stop systems with regenerative braking for both gasoline and diesel. Use 

9 
of full hybrid technology for these vehicles could bring an additional 13 to 14 percent fuel 

savings, but we did not include hybridization due to its relatively high cost. 

OVERALL FUEL CONSUMPTION REDUCTIONS IN PHASE 1 AND PHASE 2 

TABLE 5 Cost-Effective Fuel Saving Improvements across Vehicle Categories 

% Fuel 

Sha r e of Baseline 2025 Consumption Payback 

Truck Cla ss Vehicles MPG MPG Redu ction nth s2 

Sleeper Cab (high) Tractor-Trailer 50% 5.8 11.4 49.\% 13 

Sleeper Cab (low) Tractor-Trailer 13% 5.8 10.2 43.3% 10 

Da~ Cab Tractor-Trailer 37% 5.8 9.6 39.4% 17 

Tractor-Trailers 5.8 10.7 -15.9% 13 

Hybrid Vocational Vehicles 25% 6.0 11.7 48.6% 54 

No n-H br d Vocational Vehic les 75% 12.2 15.5 2 1.3% 39 

Vocational Vehicles 9. 7 1-1.3 32.3% -18 

Hea vy-Duty Pick-up/Van (gasoline) 45% 12.3 17.4 29.4% 47 

ea DulJ: Pick-ue!Van {diesel) 55% 10.5 14.3 26.3% 26 

Heavy-Duty Pick-up/ Vans 11.3 15.5 27.6% 35 

Tota l Fuel Consumption Reduction 40.6% 23 

Table 5 summarizes the efficiency improvements, oil savings, and economic payback for 

the teclmologies described above. For this summary, the midpoint values of the assessed range of 

improvements were assumed, representing a somewhat conservative estimate of the effectiveness 

of a combination of technologies. 

The technologies to improve fue l effic iency are cost-effecti ve. For example, a new 

tractor-trailer that includes an advanced engine and transmission, new axle design, and improved 

aerodynamics to the tractor and trailer could save. on average, about $30,000 per year in fuel. 

Under conservative assumptions of 103,130 average annual miles for all tractor types and $3 .65 

per gallon of diesel fuel in 2025, these new e fficiency technologies would increase truck 

purchase costs by about $32,000, whi ch is recovered by fuel savings in j ust 13 months. 

10 
450 

400 

"t:l 

.S! 350 Cll 

:> 

ro 

... 

1-

.S! "' 300 

~ 

Cll 

u 

~ 250 

> 

200 

150 

2010 

Heavy-Duty Truck Miles 

2015 2020 2025 

FIGURE I: Domestic Truck Use Expected to Rise 

2030 2035 

As more efficient new vehicles repl ace older stock in the on-road fleet, the total fleet fuel 

consumption and greenhouse gas emissions are reduced. In 2013. the on-road truck fleet 

consumed about 2.7 million barrels of oil-derived fuels per day and was responsible for emitting 

530 million metric tons of greenhouse gas emissions. ln the coming years, the demand for goods 

shipped by truck is projected to increase (EIA 20 13), resulting in more truck-miles (Figure 1). 

However, a strong second phase of standards-which could achieve a 40 percent reduction from 

new trucks by 2025 compared to 20 I 0 levels-would reduce fuel consumed by the entire onroad truck fleet to below today's levels as shown in Figure 2. Using the Argonne National 

Laboratory VISION model (J\NL 20 13) calibrated to EIA Annual Energy Outlook 20 13, we 

estimate that by 2030, the combination of both phases of standards could cut fuel use by 1.4 

million barrels per day and reduce carbon pollution by 270 million metric tons annually. 

II 
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4.5 

4.0 

... 

Q) 

Q. 

:: 3.5 

0 

0 

Qj "' 

t: 

~ 3.0 c 

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~ 

2.5 ~ 

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2010 2015 2020 2025 2030 

_._With 2010 Fue I Efficiency _._ Phase 1 Standards -o-Phase 2 Opportunities 

2035 

FIGURE 2: Truck Standards Reduce Total On-Road Fleet Fuel Consumption 

FEEDBACK AND COMMENTS FROM STAKEHOLDERS 

We presented this analysis to multiple stakeholders, including engine and vehicle 

manufacturers, equipment suppliers, regulatory agencies and environmental groups. We have 

shared our assumptions and calculation methods with them. Whi le the fuel savings estimates for 

individ ual technologies were familiar to the heavy-duty community. some clarifications were 

needed to specify test cycles on which these e fficiency numbers were generated. Some of the 

fuel efficiency numbers were generated on U.S. EPA ramped modal cycle (RMC) and may not 

be realized in real-world operation. However, our numbers are taken mostly from the mid-range, 

and thus do not claim the full potential bene fit of these technologies. Questions were also asked 

on the technology penetration rate, especially on hybrid vehicles, waste heat recovery, and 

transmission improvement. If the standards are set considering these fuel efficient technologies 

that provide reasonable payback, penetration will take place sooner rather than later in our 

assessment. In general, we received positive responses from the majority of stakeholders. For, 

example, Cummins Inc., a major heavy-duty engine manufacturer, has provided similar engine 

improvement projections for the next decade (Cummins 20 14). 

12 
CONCLUSION 

Building on the foundation laid in the first round of fuel economy and greenhouse gas 

emissions standards for medium- and heavy-duty vehicl es, a second phase of standards could 

achieve more than 40 percent fuel savings from the average new heavy-duty vehicle in 2025, 

compared to 2010. N umerous technologies have been identified that can be deployed in this 

timeframe to achieve these significant reductions in oil consumption, reducing the climate 

impacts ofthe medium- and heavy-duty tleet to 2010 leve ls despite increasing activity in the 

fre ight sector. 

Additional technologies will become available over the time period discussed here. Far 

greater tractor-trailer drag reductions appear to be possible. Aerodynamic improvement with the 

accompanyi ng engine optimization could bring major further efficiency gains. Full hybrid 

systems, once costs begin to decline, could achieve a high level of penetration in both the 

vocational and heavy-duty pickup segments. The adoption of such technologies would add 

substantially to the savings shown here. In that sense, the fuel efficiency improvements discussed 

above are merely a first step in defining an ambitious, achievable target for fue l efficiency 

improvements in the heavy-duty vehicle sector. 

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Cummins (20 13), Cummins presentation to Environment Group, Columbus, IN, dated April 15. 

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13 
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14