Summary of Interagency Working Comments Received on Draft Rule under EO 12866 Review.  Subject to

Further Policy Review

1

Below is a summary of interagency comments received during EO 12866 review of the draft 

proposed rule establishing GHG emissions standards and fuel efficiency standards for medium 

and heavy duty trucks. They are for your consideration and subject to further policy review. 

1) Alternatives to Proposed Stringency levels 

A thorough assessment of the merits of the proposed standards should assess those standards 

against alternative standards of lesser and greater stringency. With one minor exception, 

EPA and NHTSA’s rulemaking documents only evaluate their proposed standard against 

alternatives that involve different scopes of regulation with respect to the set of vehicles and 

engines covered, not against alternative stringencies. 

OMB Circular A-4 states...”You should carefully consider all appropriate alternatives for the 

key attributes or provisions of the rule. The previous discussion outlines examples of 

appropriate alternatives. Where there is a continuum of alternatives for a standard (such as 

the level of stringency), you generally should analyze at least three options: the preferred 

option; a more stringent option that achieves additional benefits (and presumably costs more) 

beyond those realized by the preferred option; and a less stringent option that costs less (and 

presumably generates fewer benefits) than the preferred option.” 

The NPRM does not propose or analyze alternative levels of stringencies for each category. 

Please analyze alternatives to proposed stringency levels similar to what was done for the 

MY 2012-2016 light duty CAFE rule. Please also include these alternatives in the NPRM for 

public comment. 

2) Alternative Baselines 

Analyzing alternative stringencies described above would also assist in addressing another 

concern: uncertainty regarding the appropriate baseline. Specifically, given that EPA and 

NHTSA finds that its standards will produce substantial net benefits to vehicle owners, it is 

possible that it may have underestimated the degree of fuel economy that would be achieved 

in the baseline. In light of this, to ensure that the merits of its standards are robust to 

alternative business-as-usual fuel economy levels, EPA and NHTSA should evaluate its 

standards against alternative baselines that assume a greater degree of fuel economy 

improvement in the baseline. Analytically, analyses of standards involving lesser-thanproposed stringency, or analyses of the proposed stringency against baselines involving 

greater-than-anticipated fuel economy would produce the same useful information that can 

be used to assess the benefits of the proposed standards both against alternatives, and in the 

face of different baselines. 

3) Restrictions on flexibilities
Summary of Interagency Working Comments Received on Draft Rule under EO 12866 Review.  Subject to

Further Policy Review

2

EPA and NHTSA propose to limit the potential use of averaging and trading provisions to 

within “regulatory classes.” This provision would increase the cost of the rule relative to an 

alternative approach that could allow broader use of averaging and trading. Moreover, an 

alternative more flexible approach would have the same, and perhaps even increased 

environmental and fuel economy benefits. Further, EPA’s and NHTSA’s decision about the 

degree of flexibility to allow for in this narrow instance should be viewed in the context of 

the precedent it may set for future EPA greenhouse gas regulations. In that context, there 

should be a strong presumption in favor of greater flexibility. 

At page 38 of the preamble, the agencies state: “the agencies propose to restrict the use of 

averaging to limited sets of vehicles and engines expected to have similar emission or fuel 

consumption characteristics. For example, averaging would be allowed among Class 7 lowroof day cab vehicles, but not among those vehicles and Class 8 sleeper cabs or vocational 

vehicles. Also, we propose that credits generated by vehicles not be applicable to engine 

compliance, and vice versa.” At page 189, the agencies state: “In the current program, 

manufacturers are restricted to only averaging, banking and trading credits generated within a 

regulatory class.” 

These restrictions in the potential use of flexibility provisions will increase the cost of the 

rule (potentially substantially so) relative to an alternative approach that allows averaging 

and trading across regulatory classes and across vehicle and engine compliance. The 

agencies offer two reasons for this limitation: “Engine and truck manufacturers have 

commonly expressed ... a concern that some manufacturers with a wide range of product 

offerings spanning a number of regulatory categories would be able to use the ABT program 

provisions to generate credits in regulatory class markets where they face less competition 

and then use those credits to compete unfairly in other regulatory categories where they face 

greater competition. Second, we have recognized that the estimation of emission credits is 

not an absolutely precise process and actual emission reductions or increases ‘in-use’ will 

vary due to differences in vehicle duty cycles, maintenance practices and any number of 

other factors. By restricting credit trading between like products, the agencies gain some 

degree of assurance that the operation and use of the vehicles generating credits and 

consuming credits will be similar.” (p. 189). Neither of these reasons strikes us several 

reviewers as a sufficient basis for restricting averaging and trading, and thereby foregoing 

potentially substantial cost savings. First, if the opportunity does in fact exist for 

manufacturers to cross-subsidize certain products via their use of fuel economy credits, they 

presumably already have that capability via their pricing decisions alone. The incremental 

effect of allowing trading of these credits across classes is therefore likely limited. Second, it 

is not clear that impacts on competitive dynamics in a market should be sufficient rationale to 

forego realizing overall cost savings. Finally, the agencies can certainly take particular steps 

to ensure that averaging and trading across classes either is environmentally neutral (or even 

beneficial), or introduces no less uncertainty than averaging and trading across heterogeneous 

vehicles and vehicle applications within a given class. 
Summary of Interagency Working Comments Received on Draft Rule under EO 12866 Review.  Subject to

Further Policy Review

3

For these reasons, we strongly recommend that the agencies remove restrictions on 

flexibilities. 

4) Alternative compliance fee 

Given the substantial uncertainty about the true cost of this rule, we believe that some firm 

cost containment mechanism, such as an alternative compliance fee, should be considered. 

Did EPA and NHTSA already evaluate whether or not such a cost containment mechanism 

could be incorporated into the proposed rulemaking? 

5) Probabilistic Uncertainty Analysis OMB Circular A-4 states, “For major rules involving 

annual economic effects of $1 billion or more, you should present a formal quantitative 

analysis of the relevant uncertainties about benefits and costs. In other words, you should try 

to provide some estimate of the probability distribution of regulatory benefits and costs. In 

summarizing the probability distributions, you should provide some estimates of the central 

tendency (e.g., mean and median) along with any other information you think will be useful 

such as ranges, variances, specified low-end and high-end percentile estimates, and other 

characteristics of the distribution.” 

The RIA does not include a formal probabilistic uncertainty analysis, as opposed to the light 

duty vehicle rule. Please provide this analysis. Further discussion of particular sources of 

uncertainty is provided below. 

6) Estimates of costs and benefits 

Several reviewers had concerns about the timeline used to estimate the rule’s costs and 

benefits, as presented in Section VIII of the NPRM and discussed in further detail in the RIA. 

Costs and benefits of model year 2014 to 2018 standards have been estimated for every year 

from 2012 to 2050 as if the 2018 standards remain in place for model years through 2050. 

This results in the aggregate estimates of costs and benefits being largely driven by long-term 

values (i.e., beyond 2020) associated with the impacts of the standards on trucks 

manufactured decades in the future. However, both costs and benefits are measured against a 

baseline fuel economy associated with MY 2010 vehicles that is assumed to remain constant 

through 2050. The selection of a constant baseline is problematic for estimating long-term 

costs and benefits, particularly given assumptions about declining technology costs and 

increasing fuel prices. For example, if historical trends in fuel economy improvements 

continue into the future, there should be a point at which, even in the baseline, vehicles 

would exceed the standards proposed here. In such a case, the standards would become nonbinding, and, beyond that point in time, the program would neither impose costs nor produce 

benefits. 
Summary of Interagency Working Comments Received on Draft Rule under EO 12866 Review.  Subject to

Further Policy Review

4

More generally, given that the question at hand relates to the merits of standards for MY 

2014 to MY 2018, and the standards will almost certainly be revisited in response to new 

information in future years, the results of analysis of these standards should not be driven, as 

they currently are, by estimates of the standards’ effects on trucks manufactured decades into 

the future. 

In light of the above, we suggest that EPA and NHSTA re-evaluate the approach taken to 

presenting estimates of costs and benefits, and shift the focus of this analysis to the near- and 

medium-term costs and benefits of the rule. For example, one possible option would be to 

estimate costs and benefits for only MY 2014 to MY 2018 trucks, over their estimated useful 

lifetimes. Other approaches could also be used. Presumably, this would not require new 

analysis, but rather simply altering what is drawn from the existing analysis to present in the 

preamble and RIA. 

7) Market Failure 

Much of the agencies’ argument for why regulation is needed in the truck market is 

predicated on the NAS report assertion that “there are commonly acknowledged 

characteristics in the commercial truck and buses marketplace that may be improved by a 

regulatory approach, such as split incentives between owners and operators (e.g., trailers) and 

the short payback period of 18 months to 2 years.” 

a) Please provide citations supporting the statement that new truck buyers require 

a short payback period (i.e,, presumably as manifested by an inappropriately 

high discount rate) for fuel saving technologies and seek comment on whether 

this is accurate. 

b) The “split-incentives” hypothesis is testable (as should be many, if not all of the 

other hypothesized market failures). Have the agencies (or researchers) ever 

tested the split-incentives hypothesis empirically? If so, please provide cites and 

a summary of those results. If not, please indicate in the preamble that there is 

no empirical evidence confirming this hypothesis and seek data that will enable 

the agencies to test it and determine its magnitude before issuance of a final 

rule. 

Regarding the discussion of reasons why the trucking market does not adequately internalize 

the fuel efficiency gains from employing available technologies (starting on p.303 of the 

NPRM): Reason #(1) cited is that trucking companies do not have adequate information 

about technologies available or the fuel efficiency of various trucks. 
Summary of Interagency Working Comments Received on Draft Rule under EO 12866 Review.  Subject to

Further Policy Review

5

c) OMB Circular A-4 states that “If intervention is contemplated to address a 

market failure that arises from inadequate or asymmetric information, 

informational remedies will often be preferred.” Did EPA and NHTSA 

consider the provision of more information? For example, manufacturers of 

vehicles with GVW over 8500 could be required to test and report fuel economy. 

Please assess the benefits and costs of providing fuel economy information to 

prospective purchasers of the engines and vehicles the proposal would regulate, 

with particular attention to EPA’s experience with SmartWay, which is 

essentially an informational program as opposed to a regulatory one. 

Regarding the reasons: several reviewers were concerned that reason #(4) “Uncertainty about 

Future Cost Savings” (p.306 of NPRM) may not represent the economics literature completely 

accurately. 

 The two Metcalf papers from 1995 are about irreversible investments in home energy 

items such as attic insulation, which has no resale value, and where consumers have 

an “option value” of waiting before investing. (See Hassett and Metcalf. 1993. 

“Energy Conservation Investment: Do Consumers Discount the Future Correctly?” 

Energy Policy.) That line of reasoning does not apply to trucks, which have a resale 

value. 

 Metcalf and Hassett (1999), footnoted but not discussed, shows that engineering 

estimates of efficiency gains from home energy purchases exceed the actual 

efficiency gains in practice, and that if actual gains are considered, consumers’ 

investment decisions look much more rational and in line with market discount rates. 

That line of reasoning would suggest there are little private net benefits from this rule. 

 The Greene paper is about loss-aversion, a behavioral phenomenon more relevant to 

individual consumers than trucking businesses that are contemplating investments 

that would yield savings one of their highest operating costs. 

d) Given the points raised above, please provide empirical evidence for reason #4 

that would be applicable to the market for commercial trucks. 

Reason #(5) “Adjustment and Transactions Costs” suggests that these new technologies “are 

likely to be adopted over time without market intervention, but with delays.” The implication is 

that by 2020 or 2030, many of these technologies might have widespread adoption without the 

fuel economy mandate. 
Summary of Interagency Working Comments Received on Draft Rule under EO 12866 Review.  Subject to

Further Policy Review

6

e) Does that not mean that the benefits in those years of mandating the technologies 

(or their accompanying fuel efficiencies) are zero? 

f) More generally, the analysis appears to assume there will be no gains in fuel 

efficiency without the rule: does the analysis then overstate the benefits of the 

rule? Figure 1-4 in the RIA shows that fuel economy in trucks more than 

doubled from 1975 to 2005. How much of the doubling is due to technology, as 

opposed to changed driving patterns, freight characteristics, and capacity 

utilization? Would the part of the trend due to technology not continue, even if 

at a slower pace? 

The relevant payback period for the suggested technology adoption is short (less than a year for 

vocational and combination trucks, according to the RIA p. 320-321). This suggests that 

information asymmetries in the used truck market may not be the cause of inefficiently low 

technology adoption. Since most combination tractors are typically sold after three to five years 

or more (see for example RIA p. 1-27), the investment should be recouped well before the truck 

is offered on a secondary market. 

g) Please explain (with supporting empirical evidence) how payback periods 

shorter than the average age of a used truck can be consistent with new truck 

purchasers not opting for fuel-saving technologies. 

8) Credits for advanced technologies 

EPA and NHTSA propose offering additional “special credits” for “advanced technologies”, 

naming electrical vehicles and hybrid powertrain as examples of advanced technologies that 

could earn these credits. There are many different government interventions seeking to 

promote research, development, and deployment of various new technologies, including 

these vehicle technologies. Given that no statutory mandate exists to do so, use of these 

standards as a mechanism for promoting particular technologies raises concerns regarding 

whether this standard should be used as a means to promote particular technologies — rather 

than being a technology-neutral standard. Such special credits, all things equal, may carry 

with them an unknown cost and otherwise make the rulemaking less effective at achieving 

environmental and fuel economy benefits. Finally, as a technical matter, the proposed 

rulemaking suggests that electric vehicles could be credited as if they have no greenhouse gas 

emissions associated with their use. 

9) Innovative Technology Credits -- Similar to the concern raised above, to what degree is 

EPA choosing technologies by giving extra credit (essentially, funds, because the extra 

credits are tradable) to manufacturers that develop new technologies that EPA and NHTSA 

decide are worthy? (See p. 205-209 of the preamble.) The reviewers recommend revising 
Summary of Interagency Working Comments Received on Draft Rule under EO 12866 Review.  Subject to

Further Policy Review

7

the proposal to encourage innovation, without mandating that EPA serve as the arbiter of 

which technologies deserve extra credit. 

a. What is actually covered under “innovative technologies?” In other words, 

how do we make sure there is a transparent process, in which EPA publicly 

discloses which technologies it awards extra credit, (i.e. what is considered 

“off-cycle”)? 

b. What is the expected value of the total amount of credits generated on an 

annual basis under the innovative technology proposal? 

c. Lastly, if EPA and NHTSA are providing tradable credits to reward 

manufacturers for developing certain new technologies, shouldn’t this be 

subject to the appropriations process? How is this different from DOE 

providing grant funds to the private sector to stimulate the development of 

new technologies? 

10) Compliance Preview Meetings -- EPA should take comment on the degree to which 

compliance preview meetings (“which provide the Agency an opportunity to review a 

manufacturer’s new product plans and ABT projections,” according to page 211 of the 

preamble) would affect normal business practices and constitute a burden in terms of both 

added cost and time to the product development cycle. Also, the RIA does not appear to take 

these costs into account. 

11) Compliance Testing Strategy -- How does EPA plan to address compliance testing in future 

iterations of this rule? Does the agency plan to develop a full vehicle standard? What are the 

pros and cons of testing compliance using a model (e.g. [TEST]) versus building a full 

vehicle test cell in the Ann Arbor Lab and requiring industry to build identical test cells? 

What are the costs associated with building these test facilities? What are costs associated 

with building additional chassis dynamometer test cells, both for EPA and for industry? 

Also, will [TEST] need to be validated on an ongoing basis, or will it be “validated” once 

the peer review is completed? 

12) Early option credits 

NHTSA proposes allowing manufacturers to voluntarily opt in to their HD program in 2014 

or 2015, and thereby generate early credits. Given that such manufacturers will have to meet 

EPA standards over this time period, we would appreciate further clarification about how the 

early credit option would work while avoiding the creation of strategic incentives for opting 

in. For example, it seems possible that the early credit option could offer more efficient 

manufacturers an opportunity to strategically opt in while less efficient manufacturers do not, 

thus creating an excess supply of credits for the period beyond 2015. 
Summary of Interagency Working Comments Received on Draft Rule under EO 12866 Review.  Subject to

Further Policy Review

8

 

13) Evaluation of uncertainty 

The assessment of costs and benefits would be improved by further sensitivity analysis of 

some key uncertain variables. For example, given the centrality of fuel prices to the 

estimates of payback periods and net benefits, further sensitivity analysis of fuel prices would 

shed light on the robustness of the proposed standards. Other examples of potentially 

significant sources of uncertainty are technology costs, rates of learning, technology adoption 

rates, and vehicle lifetimes. 

14) RPE and Learning curve: Please discuss the rationale for deviating from the NAS 

recommendation on RPE. Also, please provide evidence for the time learning curve used in 

the analysis. Given that the regulation doesn’t appear to be very technology forcing, please 

provide evidence for taking 2 learning curve discounts, which serves to lower the cost of the 

rule and is in total is a more aggressive learning curve then the agencies have used in the 

past. Please clearly present the costs with and without learning discounts (probably in a 

tabular form would be the best). Also, how were the fixed costs spread over the relevant 

trucks/trailers? 

15) Simulation Model 

The analysis contains references to TEST, but there aren’t many details about exactly how 

the agency estimated the key parameters in the model (e.g., numbers of data points) or how 

it uses the various inputs to calculate reductions. Such information would be useful for the 

public in evaluating the effectiveness of the model in providing reasonable estimates of the 

impact of the rule. Has this model been published and peer reviewed? Please include the full 

code and model in the NPRM for public comment. Are there other models that achieve the 

same purpose? Do manufactures have models? Are there other third party developed models 

available? Would there be any differences between this model and any in house testing that 

manufactures already developed? Will they get similar ratings or will they notice significant 

differences? 

16) Costs and Cost Effectiveness 

It is unclear from Chapter 2 of the RIA exactly where the agencies got the cost estimates 

from. There are general citations to NAS and TIAX and other studies but the agencies never 

specifically pinpoint which technology cost estimate came from which study. Please provide 

a detailed chart with the following info: name of technology, cost estimate of technology, 

citation for where this cost estimate is based off of, and analysis of cost effectiveness. 
Summary of Interagency Working Comments Received on Draft Rule under EO 12866 Review.  Subject to

Further Policy Review

9

17) Treatment of Fuel Savings in RIA and NPRM 

The agencies include fuel savings in the cost category throughout the RIA and NPRM. 

Please include this category only in the benefits section because fuel savings are benefits not 

costs. Please make this change throughout the RIA and NPRM. 

18)Information to consumers.

Several commenters suggest that EPA and NHTSA consider and take comment on 

approaches for providing information to consumers that will enable them to make decisions 

that maximize their utility, factoring in efficiency and environmental information. As the 

NPRM is currently written, the Agencies believe that they are unable to provide meaningful 

information along these lines because of the diversity of HD vehicles and uses and the many 

assumptions that would need to be made. It would be useful to query whether this NPRM 

presents an opportunity to seek comment on how the Government could facilitate greater 

access to more detailed information for HD vehicles, similar to what has been accomplished 

for passenger vehicles both on labels and through the Fuel Economy Website. 

19) Leakage effect from impacts on global fuel prices—

EPA provides a very good discussion of the problem—that a decline in domestic oil 

consumption from increased fuel economy may reduce oil prices and thus lead to increased 

consumption elsewhere—but does not estimate how large that impacts would be and include 

in the cost-benefit analysis. NHTSA provides a quantitative estimate on this effect for the 

light duty rule. EPA could draw on that analysis to include a quantitative estimate of the 

leakage effect. Please include this in the RIA. 

20) Separate Standards. If CO2 (or CO2 equivalent) is a linear function of gallons of fuel 

consumed, why propose separate standards for fuel economy and CO2/mile? Why the 

separate phase-in times for the two different rules? Could not the same regulatory goal be 

achieved with just the simple gallons per 1000 ton-mile standard, with less confusion? (See, 

eg., page 85 of the preamble.) 

21) Analytic Timeline and baseline: Please clarify whether the rulemaking pertains to only 

trucks and trailers manufactured between 2014 through 2018, and accordingly the analysis. 

Are the trucks/trailers produced in 2019 and on included in the analysis? What is the 

anticipated scope of the rulemaking—e.g., number of trucks/trailers affected? Number of 

firms affected? Number of drivers affected? What does this industry look like in the 

absence of this rule? Some technologies are already commercially available and have been 

adopted (e.g., trailer aerodynamics) 
Summary of Interagency Working Comments Received on Draft Rule under EO 12866 Review.  Subject to

Further Policy Review

10

22) Tires: How does this NPRM affect the retreading of tires? Is there any weather-related 

safety concern with reduced tire rolling resistance? 

23) Weight reduction: Do EPA/NHTSA anticipate that this NPRM will affect the markets for 

aluminum and titanium? 

24)Idle control: Please provide the basis for assumed idle hours per year, miles per year and 

payload (Table 2-22). 

25) Difficulty in assessing technology control costs, effectiveness of controls, and benefits: 

It’s difficult to link Tables 2-23, 2-24, 2-25, and 2-26 to the benefits section. Please clarify. 

Same comment applies to the vocational trucks as well. 

26) Tire pressure monitoring system: Doesn’t DOT already have a rule in place to deal with 

this? 

27) Route planning: What are the costs associated with adoption of this strategy? Also, firms 

already seem to have a large incentive to optimize routing as a business practice, and it is 

not clear that the rulemaking would provide a strong additional incentive. 

28) HFC: Please discuss and estimate the HFC-134a consumption baselines under two 

scenarios: (1) the US proposal to amend the Montreal Protocol gets adopted; (2) the US 

proposal to amend the Montreal Protocol does not get adopted. Also, please assess the 

reduction of HFC-134a consumption that is attributable to this rulemaking. 

29)Increased congestion cost: Please clarify how the costs are estimated? Also did EPA and 

NHTSA estimate additional accidents? 

30) Time value associated with reduced refueling: How many refills in the baseline? What is 

the assumed time saved per refill? 

31) Fuel savings: What is the assumed price of fuel used in fuel savings calculations? What is 

the source of the price information? 

32) Please seek comment on the safety effects of low rolling resistance tires for trucks. 

33) It would be useful to provide estimates of the likely percentage increases in truck prices as a 

result of the rule. 
Summary of Interagency Working Comments Received on Draft Rule under EO 12866 Review.  Subject to

Further Policy Review

11

34) Please provide a fuller discussion of the assumptions used to construct the baseline. What, 

for example, is assumed about the adoption of low rolling resistance tires in the absence of 

the rule? 

35) Please clarify- It seems the agencies are not considering weight of tractor but considering 

only weight reduction in wheel and tires? If using modeling, why does it matter how much 

weight reduction is? It seems how much the entire vehicle weighs matters more than how 

much weight reduction there is. If you are only interested in weight reduction, what is it 

compared to? And why only consider weight reduction in tires and wheels? How are they 

different from rest of the vehicle? 

36) Given the size of the RIA, it would be useful to have a discussion and a table that provides a 

list of the key assumptions used in the cost and benefit estimates, e.g. annual mileage of 

trucks, cost of fuel, life of trucks, number and kind of each truck sold. This will add to the 

transparency and reproducibility of the analysis. 

37) Absent standards, if trucking companies wanted to save fuel, they would choose the lowestcost strategies to reduce fuel consumption. This might involve more driver training or 

purchase of optimal routing technologies. However, if standards are set, trucking 

companies may be forced into higher cost ways of saving fuel. Some might argue that once 

standards are set, trucking companies will still have an incentive to engage in the lower cost 

strategies that are outside of the standards setting, but this may not be true. Having more 

fuel efficient trucks makes engaging in management and driver training less profitable for 

trucking companies. So high-cost fuel saving technologies may “crowd out” lower cost 

strategies that are outside of standard setting. Please provide an estimate of this lost fuel 

economy and seek comment on this point. 

38) The North American Free Trade Agreement required the US to allow access to Mexican 

trucking companies starting in 2000, though that dispute is still ongoing. 

 Is there a concern that this regulation could cause truck assembly plants or sales 

offices to move to Mexico, to sell trucks to Mexican trucking companies operating in 

the US, thereby avoiding the fuel economy standards? 

 More generally, how, if at all, does this rule interact with the NAFTA trucking 

dispute? 

39) P.38 of Preamble. “we propose that credits generated by vehicles not be applicable to 

engine compliance, and vice versa.” 
Summary of Interagency Working Comments Received on Draft Rule under EO 12866 Review.  Subject to

Further Policy Review

12

 Can the agencies elaborate? It sounds like this restriction misses an opportunity for 

reducing the cost of achieving fuel economy. 

40) Why are fleet turnover effects not estimated? 

‐ We suggest the RIA document the sensitivity of the benefits to a reasonable guess as to 

the size of the fleet turnover effect. Suppose, for example, that regulations cause truck 

companies to delay by one year their purchase of new trucks, increasing the average age 

of the fleet. By how much would that diminish the estimated fuel economy savings and 

CO2 emissions reduction? 

41) ORNL estimates the macro premium at $4.68/bbl in 2004$. That would be $5.33 in 2008$. 

Why does the RIA use $7.39? 

42) Did the agency consider as an “alternative” a fuel tax, along the lines of the 

recommendation in the NAS report? 

43) Both the RIA and the preamble devote space to estimating the effect of the rule on GDP. 

Both are careful to note that changes in GDP do not represent either benefits or costs of the 

rule. Is there a reason those estimations are included in the two documents, and if not can 

they be dropped? 

44) Early adoption credits for NHTSA Fuel Economy Rule. Our understanding was that 

because GHG is a linear function of gallons, there is really no logical reason to have two 

separate policies. The only reason there are two policies here is that the two agencies have 

slightly different statutory obligations, and that in particular NHTSA is required to wait 

longer than EPA before implementation. Further, we think and hope it is true that the two 

standards are designed so that there are as few differences between them as possible: if I 

comply with one, I automatically comply with the other, and vice versa. In that case, if I 

must comply with the EPA standard before I am required to comply with the NHTSA 

standard, don’t I automatically “voluntarily” comply with the NHTSA standard. And if that 

is true, should we be giving credits for actions firms are effectively required to take? 

45) Parallel to consumer welfare loss in the April CAFE rule. The CAFE rule issued in April 

also struggled with the issue of why consumers don’t themselves take advantage of fuel 

efficiency gains. That RIA had something this RIA misses: a sensitivity analysis. Table 

VIII-18 of the RIA for that rule estimates the net benefits of the fuel economy standards for 

light duty vehicles where the private benefits are reduced by 25 % and 50%, to account for 

potential welfare losses from switching to less-preferred more efficient vehicles. See the 
Summary of Interagency Working Comments Received on Draft Rule under EO 12866 Review.  Subject to

Further Policy Review

13

final RIA, p.431-32 (http://www.nhtsa.gov/staticfiles/rulemaking/pdf/cafe/CAFE_2012-

2016_FRIA_04012010.pdf) 

Did the agencies consider a similar sensitivity analysis for this rule? If so, why was it 

omitted? If not, would they consider including it now. It would not require much work 

beyond an additional table and a few paragraphs of prose, most of which could be 

adapted from the light duty RIA. If anything, such an analysis would be more important in 

this rulemaking, as the “consumers” in this case are businesses with a presumably strong 

incentive to lower what is one of their largest operating costs, even if they don’t suffer the 

full cost of the externalities associated with their fuel use decisions. 

46) Unit Used for Regulations 

The NAS report “Technologies and Approaches to Reducing the Fuel Consumption of Mediumand Heavy-Duty Vehicles”, dated March 17, 2010, highlights the critical importance of selecting 

an appropriate unit to represent the work performed by the truck. The current EPA/NHTSA 

document interchangeably uses “fuel economy” and “fuel consumption” without providing any 

specificity on the metric to be used for regulations. These reviewers agree with the NAS 

recommendation 2-1 stipulating that “Any regulation of MHDVs fuel consumption should use 

load-specific fuel consumption (LSFC) as the metric and be based on using an average (or 

typical) payload based on national data representative of the classes and duty cycle of the 

vehicle.” 

The NPRM does not explain the desirability of regulating on the basis of cargo ton-mile of 

operation as opposed to other metrics. We believe that the NPRM should discuss the current 

philosophy of regulation of light duty passenger vehicles and ask whether it is appropriate for 

heavy duty vehicles. The report by Bertram et al should be included as a reference. 

The terms “ton-mile” and “gallons-per-ton-mile” should be included in the list of acronyms and 

text discussion. 

47) Point of Regulation 

Even though the NAIC code of the parties to be regulated are provided the NPRM discussion 

could be clearer on where the point the regulation would be. 

48) Drive cycle. 

The average speed of each driving cycle, as well as statistics such as number of stops per mile, 

percent of time roadway idling, percent of time overnight idling, top speed, share of miles on 

interstates should be provided. Some, though not all of the driving cycle statistics that would be 

relevant are found in the EVS-21 paper. We suggest a similar, but more thorough discussion. 
Summary of Interagency Working Comments Received on Draft Rule under EO 12866 Review.  Subject to

Further Policy Review

14

The “Higher Productivity Vehicle Report” of the American Transportation Research Institute 

and the general topic that it discusses (larger trucks) should be a reference. It can be obtained at: 

http://www.atri-online.org/index.php?option=com_wrapper&view=wrapper&Itemid=84 

The ATRI report presents results based on a driving cycle that is appropriate for class 8 tractor 

trailers – the “combination long-haul” case. Such a driving cycle should be included in the RIA. 

The question of how to develop a fleet fuel consumption estimate per cargo ton-mile carried 

should be discussed, and the groupings over which it should be done should be examined. 

On page 335 of the Preamble, the first full paragraph, "The first three values are based on the 

average SCC from three integrated assessment models, at discount rates of 2.5, 3, and 5 percent, 

respectively." should be "The first three values are based on the average SCC from three 

integrated assessment models, at discount rates of 5, 3, and 2.5 percent, respectively." 

Specific Comments 

49) Page 1-39. The document incorrectly describes Plug-in Hybrids as “The third type of HD 

hybrid vehicle is a ‘plug-in’”. Hybrids can be electric or hydraulic as correctly mentioned. 

PHEVs simply mean that the battery can be recharged from a plug. They are in fact electric 

hybrids. 

50) Page 2-64 First bullet says “The internal combustion engine can be optimized (through 

downsizing, modifying the operating cycle, or other control techniques) to operate at or 

near its most efficient point more of the time”. We think the text meant to say that “the 

powertrain control strategy can be developed to operate the engine at or near its most 

efficient point most of the time”. 

51) Page 2-64, second paragraph mentions “Although plug-in hybrids are not considered 

feasible for truck applications for propulsion power, this mechanism is explored further for 

trucks in a separate section discussing extended idle”. Several OEMs are currently working 

on PHEV trucks for propulsion. Some applications with low distances, such as P&D, are 

very well suited to these configurations. In addition, while we agree that the current status of 

the battery makes a wide implementation difficult, future technologies will most likely 

expand the powertrain choice option for more applications. The statement above should be 

revised to be less definitive concerning the feasibility of PHEVS. 

52) Page 2-66, first paragraph mentions “EPA is experimenting with a Class 6 hydraulic hybrid 

that achieves a fuel economy increase similar to electric hybrid gains and given high 

manufacturing volumes at with similar electric hybrid costs”. EPA should provide a 

reference to justify this statement. 

53) Page 3-25, section 3.1.2.6. OEMs have made it clear that, for some engine, several engine 

maps have to be used to properly characterize fuel consumption. This is especially true for 

line-haul engines. The document should specify how this will be achieved. 

54) Page 3-7, first paragraph, “Class 7/8 tractor aerodynamics are currently developed by 

manufacturers using coastdown testing, wind tunnel testing and computational fluid 

dynamics. The agencies are proposing to allow all three aerodynamic evaluation methods”. 
Summary of Interagency Working Comments Received on Draft Rule under EO 12866 Review.  Subject to

Further Policy Review

15

There is currently no consensus about how to perform any of these methods. A good 

example is wind tunnel where most of the companies have different systems and disagree 

with each other results. Providing a choice of method without proper evaluation of the 

uncertainties within each method and between methods could lead to gaming. 

55) Page 3-9, last paragraph, “Since heavy-duty coastdowns involve more uncertainty, more 

tests are required to achieve and acceptable certainty in the mean of the resulting 

coefficients. “. The term “acceptable uncertainty” needs to be quantified. 

56) Page 3-15, Figure 3-1. Similar to the previous comment, the rolling resistance coefficient 

uncertainty can lead to selecting a different bin for the model. What is the impact on LSFC? 

Will manufacturers be able to perform many tests and pick the values they want? 

57) Page 3-15, Drag coefficient section “We estimated frontal area of the International truck to 

be 99 ft2 (9.2 m2) by measuring the various dimensions of the tractor cab and other 

equipment such as exterior mirrors and tires”. A discussion of the accuracy is the 

estimation is needed. 

58) Page 3-24, Third paragraph mentions “However, the use of these type of application specific 

cycles in a regulatory scheme will lead to a proliferation of cycles for every application, an 

outcome that is not desirable.” Why only three cycles if the model can handle any type of 

cycle? Isn’t it possible to have specific representative drive cycles for each of the main 

applications (maybe ~10?). 

59) Page 3-24, section 3.4.2, The NAS report demonstrated that grade needs to be taken into 

account to properly evaluate the fuel consumption benefits of some technologies, including 

HEVs. Grade can easily be taken into account in a vehicle simulation tool. 

60) Page 3.-24, Drive cycle selection: it appears that all the drive cycles are time based rather 

than distance based. This approach is not appropriate since it does not allow a proper 

comparison of vehicles with different transmission technologies, especially for line-haul 

applications. We recommend using two drivers, one time based and another distance based 

depending on the application to ensure a fair comparison of technologies. 

61) Page 3-24, Drive cycle selection. What happens if the maximum speed of the truck is lower 

than 65 mph? 

62) Page 3-24 & 3-36, Drive cycle selection. How is the difference in idling taken into account? 

Using the same three cycles will most certainly lead to not accurately representing fuel 

displacement potential for some technologies on specific applications. For example, real 

world drive cycles with refuse trucks have shown an idle time of 77% for front-loaders, 70% 

for real loaders and only 50% for side loaders (SLA). 

63) Page 3-31, section 3.7 states “EPA and NHTSA are proposing two methods to demonstrate 

benefits of a hybrid powertrain – chassis and engine testing, and thereby generate credits 

through the use of such technology”. HEVs have been evaluated through vehicle modeling 

and simulation tools such as PSAT and Autonomie for the past decade. Requiring testing for 

advanced technologies will lead to slowing down their introduction since additional cost 

will be required compared to conventional vehicles. Different processes lead to favoring 

some technologies over other. We recommend using MIL (Model in the Loop) for 

conventional (as currently proposed) and SIL (Software in the Loop) for electric drive 
Summary of Interagency Working Comments Received on Draft Rule under EO 12866 Review.  Subject to

Further Policy Review

16

configurations. These approaches are currently the ones being considered by OEMs in 

Europe. 

64) Page 3-33, last sentence of second paragraph “It is expected that pre-transmission, parallel 

hybrids would be the most likely choice for engine-based hybrid certification.” Any 

configuration can be implemented using that process as it is currently the case within several 

OEMs and research entities. 

65) Page 3-35, second paragraph, “We are proposing to add a new optional PTO test to the 

standard set of test cycles in order for manufacturers of advanced PTO systems to 

demonstrate in the laboratory environment fuel consumption and GHG reductions that 

would be realized from their systems in the real world.” While the regulations are supposed 

to be based on vehicle modeling and simulation to be able to handle any application option, 

it appears that any specific technologies, such as PTO, HEVs... will have to be evaluated 

through testing. We believe that any technology can be properly evaluated through 

modeling and simulation given proper driving cycles and component data. 

66) Page 3-36 – Table 3-13. How generic is the percentage of PTO usage for different 

applications? 

67) Page 4-2, section 4.1.2, “‘The simulation model will be the primary tool used to certify 

Class 2b through Class 8 heavy-duty, non-hybrid truck GHG emissions.”. We believe that 

all technologies can and should be evaluated through vehicle modeling tool to avoid 

favoring technologies. 

68) Page 4-3, section 4.2.2. The section mentions that users can change any of the model 

parameters, but that they should not (page 4-5, “manufacturers cannot alter any default 

settings or select alternative drive cycles”). What is preventing users from changing 

parameters since the models are in Simulink / StateFlow? 

69) Page 4-3, section 4.2.2. Much work and time has been spent to properly model gear 

selection and gear shifting in Autonomie. How was EPA/NHTSA specific algorithm 

developed? This is a critical part of heavy duty modeling and is not discussed in this section. 

70) Page 4-5, last bullet “Alignment of data from different sources such as dynamometer 

emissions benches, portable emissions measurement systems, or engine control units”. 

Vehicle simulation tool are known to be unreliable to emission modeling. Validation results 

should be provided for the emissions. 

71) Page 4-5, section 4.3.1, Detailed information should be provided on validation results, 

including instantaneous gear shifting, engine speed, engine torque, fuel rate.. 

72) Page 4-6, section 4.4. “While several existing heavy-duty vehicle simulation models are 

widely accepted by the research community and industry, one drawback is that their codes 

are not designed for the proposed regulatory program”. This is correct, however, these 

codes have been validated over the long term on numerous applications and allow the use of 

modeling and simulation for any technologies. In addition, these codes can be very quickly 

modified for regulatory/labeling purposes. An on-going project with ACEA for HD labeling 

using Autonomie demonstrates that point. 

73) Page 4-6, section 4.4.1, “EPA proceeded with the development of a heavy-duty truck 

simulation package which produces GHG output comparable to many sophisticated 

forward-looking models,” Information supporting this statement should be provided. 
Summary of Interagency Working Comments Received on Draft Rule under EO 12866 Review.  Subject to

Further Policy Review

17

74) Page 4-7, Figure 4.1, Why is the user able to select Engine characteristics (Family, Sub 

Family, Model Year...) if one cannot change the engine data? 

75) Page 4-8, first section, “However, some technologies may create detrimental effects due to 

their usage pattern and some may be too complex to model. For example, it may be difficult 

to accurately model those improvements which are based on each manufacturer’s 

proprietary control strategies.” Difficult does not mean impossible. OEMs in Europe are 

currently pushing for the integration of proprietary control strategies into the labeling 

process. The software tools currently allow such implementation as well. This is necessary 

to properly evaluate a technology. OEMs are already modeling advanced controls, so this 

would not be an additional burden to them as long as the tool is designed for that purpose. 

76) This proposal does not include a discussion of the upstream benefits of combusting biofuels 

in lieu of conventional fuels. Those benefits are clearly articulated in the RFS2, which 

should be referenced in this document. In addition, there are several places where the 

differentiation of fossil fuel carbon dioxide from biogenic carbon dioxide and is appropriate 

(see specific references below). 

77) Also, different implementation schedules are being proposed by EPA and the National 

Highway Traffic Safety Administration (NHTSA). The NHTSA schedule gives additional 

time for manufacturers to comply with the proposed standards, and we support NHTSAs 

proposed schedule. 

78) Moreover, we are concerned with the documents that refer to the choice of diesel particulate 

emissions reduction to be handled by the manufacturer and not prescribed in detail by the 

government . To meet the current particulate emissions from diesel engines, manufacturers 

have developed several different emission strategies. Most of these involve a regeneration 

process (a superheated mode within the exhaust system that incinerates the stored 

particulates when they reach a prescribed level). The regeneration process requires the 

vehicle to either stop or operate in a reduced speed mode while it is taking place. We 

(along with other agencies that have emergency vehicles) have a need for a temporary, 

emergency by-pass to the regeneration process. Yes, the result will be isolated, 

elevated emissions until the vehicle can reach a safe place for regeneration. However, 

a by-pass technology would ensure that our fire engines (or other emergency 

equipment) would be able to safely retreat from a life- or property-threatening 

situation. We know that other state/county agencies are also concerned, as some have 

ambulances that can be forced into go-slow mode for regeneration at the time a patient 

is being transported to a hospital. (The only reference to regeneration said that the 

potentially higher emissions emitted during the regeneration process itself would not be 

measured or regulated.) 
Summary of Interagency Working Comments Received on Draft Rule under EO 12866 Review.  Subject to

Further Policy Review

18

They also support the proposed focus on chassis manufacturers (and not the body manufacturers) 

regarding vocational vehicles not otherwise covered by the HD pickup and van standards (EPA 

requested feedback on this issue). 

For #78-82 below, Please add the additional highlighted text: 

79) Page 14: “...As in the recent light-duty vehicle rule establishing CAFE and GHG standards 

for MYs 2012-2016 light-duty vehicles, EPA’s and NHTSA’s proposed standards for the 

heavy-duty sector are largely harmonized with one another due to the close and direct 

relationship between improving the fuel efficiency of these vehicles and reducing their fossil 

fuel carbon dioxide (CO2) tailpipe emissions. For all vehicles that consume carbon-based 

fuels, the amount of CO2 emissions is essentially constant per gallon for a given type of fuel 

that is consumed. The more efficient a heavy-duty truck is in completing its work, the 

lower its environmental impact will be, because the less fuel consumed to move cargo a 

given distance, the less CO2 emitted into the air. The technologies available for improving 

fuel efficiency, and therefore for reducing both CO2 emissions and fuel consumption, are 

one and the same.1

 Because of this close technical relationship, NHTSA and EPA have 

been able to rely on jointly-developed assumptions, analyses, and analytical conclusions to 

support the standards and other provisions that NHTSA and EPA are proposing under our 

separate legal authorities...” 

80) Page 29: “...The proposed EPA and NHTSA standard curves are based on a set of vehicle, 

engine, and transmission technologies expected to be used to meet the recently established 

GHG and fuel economy standards for model year 2012-2016 light-duty vehicles, with full 

consideration of how these technologies would perform in heavy-duty vehicle testing and 

use. All of these technologies are already in use or have been announced for upcoming 

model years in some light-duty vehicle models, and some are in use in a portion of HD 

pickups and vans as well. The technologies include: 

 advanced 8-speed automatic transmissions 

 aerodynamic improvements 

 electro-hydraulic power steering 

 engine friction reductions 

 Use of biofuel blends 

                                                           

1

 However, as discussed below, in addition to addressing CO2, the EPA’s proposed standards also include provisions 

to address other GHGs (nitrous oxide, methane, and air conditioning refrigerant emissions).), as required by the 

Endangerment Finding under the Clean Air Act. See Section II. 
Summary of Interagency Working Comments Received on Draft Rule under EO 12866 Review.  Subject to

Further Policy Review

19

 Improved accessories 

 low friction lubricants in powertrain components 

 lower rolling resistance tires 

 lightweighting 

 gasoline direct injection 

 gasoline engine coupled cam phasing 

 diesel aftertreatment optimization 

 air conditioning system leakage reduction (for EPA program only) 

81) Page 258-259: “...EPA used MOVES to estimate downstream GHG inventories from these 

proposed rules. We expect reductions in fossil fuel CO2 emissions from all heavy-duty 

vehicle classes. The reductions come from engine improvements and road load 

improvements. EPA expects CH4 and N2O emissions to increase very slightly because of 

VMT rebound and because significant vehicle reductions are not expected from these 

proposed rules. Overall, downstream GHG emissions (CO2eq) will be reduced significantly, 

and is described in the following subsections. For fossil fuel CO2 and fuel consumption, the 

total energy consumption “pollutant” was run in MOVES rather than CO2 itself. The energy 

was converted to fuel consumption based on fuel heating values used in the development of 

MOVES emission and energy rates2. These values are 122,893 kJ/gallon for gasoline and 

138,451 kJ/gallon for diesel. To calculate CO2, the agencies assumed a CO2 content of 

8,887 g/gallon for gasoline and 10,180 g/gallon for diesel. (EPA requests comment on how 

to calculate biogenic CO2 emissions from biofuel mixes of gasoline and diesel with ethanol 

and biodiesel)...” 

82) Page 260: Table 0-1: Annual Upstream GHG Emissions Reductions in 2018, 2030, and 

2050 Add column. 

 Fossil 

Fuel CO2

(MMT) 

Biogenic 

CO2 

(MMT) 

Fossil 

Fuel CH4

(MMT 

CO2eq) 

N2O 

(MMT 

CO2eq) 

Total GHG 

(MMT 

CO2eq) 

2018 4.5 0.8 0.02 5.3 

2030 12.7 2.0 0.06 14.7 

                                                           
Summary of Interagency Working Comments Received on Draft Rule under EO 12866 Review.  Subject to

Further Policy Review

20

2050 19.8 3.1 0.10 22.9 

83) Page 273: Emissions Inventory Impacts 

Upstream Impacts of the Program 

***[Include discussion of fossil fuel CO2 emission reductions from use of biofuels] 

84) What exactly is being proposed? This document is full of detailed information, and is very 

hard to navigate. We highly recommend a more thorough executive summary for easier 

reading by the public. We also suggest including easy-to-understand charts up front that 

spell out the elements of the proposed rule and the associated costs and benefits. 

85) How would increasing the weight limit on trucks in certain areas affect these rules? E.g. 

would a truck be able to haul 100,000 lbs. and still comply with the fuel efficiency 

standards? 

86) Have you considered allowing a higher weight limits on trucks as an alternative? That is, 

allowing trucks to haul more weight would theoretically allow for fewer trucks, which 

would reduce overall CO2 output per ton-mile. 

87) Are there safety implications for the various technology improvements? E.g. reducing the 

rolling resistance on tires seems to contradict safety goals. 

88) The section on "How would this proposed program impact fuel consumption, GHG 

emissions, and climate change", from page 256 -273, most of what is discussed regarding 

GHG and climate change is cited (to CCSP and USGCRP). However, EPA's estimates (page 

272) on how the program would affect temperature increases and ph levels of the ocean is 

marked with a placeholder (no numbers), so there's not much we could say about that 

number (whether or not it is realistic, etc) or determine if the methodology is actually 

correct. Please provide this information so that we can evaluate the methodology.