Summary of Interagency working comments received on draft rule under EO 12866 and EO 13563 

review. Subject to further policy review. 

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Below is a summary of interagency comments received during EO 12866 and EO 13563 review of the 

draft final 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. 

Interagency comments on Alternative Fuels discussion in Preamble: 

NHTSA recognizes that EPCA/EISA promotes incentives for alternative fueled vehicles for 

different purposes than does the CAA, and that there may be additional energy and national security 

benefits that could be achieved through increasing fleet percentages of natural gas and other alternativefueled vehicles. More alternative-fueled vehicles on road would arguably displace petroleum-fueled 

vehicles, and thereby increase both U.S. energy and national security by reducing the nation’s dependence 

on foreign oil. However, the agencies believe that the benefits of harmonization would outweigh any 

potential gains in this area. In addition to reducing industry burden and creating regulatory efficiency, a 

harmonization rule both adheres to the President’s May 2010 memorandum calling for a joint 

rulemaking,1 and Executive Order 13563.2

The agencies believe that a divergence of standards in this area would have significant negative 

consequences. Dis-harmonization would effectively make the NHTSA program irrelevant, but would 

increase burdens for both manufacturers and the agencies in the areas of compliance and reporting. 

Further, dis-harmonized standards would likely lead to credit excesses in NHTSA’s program for which 

there would be no demand.

On the other hand, achieving harmonized standards has many benefits for the public, the 

regulated industries, and the agencies. 

By reducing regulatory inefficiency, harmonization decreases costs for all parties involved, 

including taxpayers. Harmonization also allows manufacturers to project clear benefits for the application 

of GHG-reduction and fuel efficiency technologies, thus spurring their adoption, and reduces incentives 

for gaming the regulatory system instead of achieving real GHG and fuel efficiency benefits.

This combined rulemaking by EPA and NHTSA is designed to regulate two separate 

characteristics of heavy duty vehicles: greenhouse gas emissions (GHG) and fuel consumption. In the 

case of diesel or gasoline powered vehicles, there is a one-to-one relationship between these two 

characteristics. Each gallon of gasoline combusted by a truck engine generates approximately 8,887 

grams of CO2; and each gallon of diesel fuel burned generates about 10,180 grams of CO2. Because no 

available technologies reduce CO2 emissions per gallon of fuel combusted, any rule that limits CO2 

emissions is effectively identical to a rule that limits fuel consumption. Compliance by a truck 

manufacturer with the NHTSA fuel economy rule assures compliance with the EPA rule, and vice versa. 

For alternatively fueled vehicles, which use no petroleum, the situation is different. For example, 

a natural gas vehicle that achieves approximately the same fuel economy as a diesel powered vehicle 

would emit 20 percent less CO2; and a natural gas vehicle with the same fuel economy as a gasoline 

vehicle would emit 30 percent less CO2. Yet natural gas vehicles consume no petroleum. To the extent 

 

1 Improving Energy Security, American Competitiveness and Job Creation, and Environmental Protection Through a 

Transformation of Our Nation’s Fleet of Cars And Trucks,” Issued May 21, 2010, published at 75 FR 29399, May

26, 2010. 2 EO 13563 states that an agency shall “tailor	its	regulations	to	impose	the	least	burden	on	society,	consistent	

with	obtaining	regulatory	objectives,	taking	into	account,	among	other	things,	and	to	the	extent	practicable,	

the	costs	of	cumulative	regulations,”	and	“promote	such	coordination,	simplification,	and	harmonization”	as	

will	reduce	redundancy,	inconsistency,	and	costs	of	multiple	regulatory	requirements.

Comment [A1]: Interagency commenter 

recommends agencies delete this sentence, for three 

reasons.. 

(1) “Regulatory Efficiency” is not defined, and could 

easily mean “achieves objective at least cost. Since 

the objective of the NHTSA rule is reducing oil 

consumption, classifying vehicles according to their 

GHG emissions would not achieve “regulatory 

efficiency”. 

(2) Joint rulemakings to not need to result in 

identical rules. See the Light Duty joint rulemaking. 

(3) EO 13563 also calls for flexibility and costeffectiveness. Setting fuel standards according to 

GHG emissions is not cost effective. 

Comment [A2]: Interagency commenter 

recommends agencies delete this sentence. It was 

discussed before: 

(1) Allowing the standards to diverge, as in the 

light duty rule, would only make NHTSA irrelevant 

if the currently proposed fuel economy standards 

were maintained. The point is that those could be 

tightened, achieving even better fuel economy, at 

lower cost due to the incentives for NGVs. 

Again, see the light duty rule. Are the NHTSA 

standards irrelevant there? The point is, some 

manufacturers would be bound by the NHTSA rule 

and others by the EPA rule. 

(2)Under the current framework, isn’t the NHTSA 

standard irrelevant, in the sense that it is redundant. 

No manufacturer would be in compliance with one 

rule and not the other. Complying with the EPA 

rule means automatic compliance with the NHTSA 

rule. Therefore, it is the current framework under 

which NHTSA is irrelevant. 

Comment [A3]: Interagency commenter 

recommends that the agencies delete this sentence, 

or define regulatory efficiency and explain how 

taxpayers benefit from identical rather than 

individual rulemakings. 

Comment [A4]: Interagency commenters 

recommend that agencies delete this sentence. 

Commenters have asked numerous times for an 

explanation of how this system could be “gamed.” 

What does it mean that harmonization “allows 

manufacturers to project clear benefits”? 
Summary of Interagency working comments received on draft rule under EO 12866 and EO 13563 

review. Subject to further policy review. 

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that the goal of the NHTSA fuel economy portion of this rulemaking is to curb petroleum use, then 

natural gas vehicles should be credited with zero fuel consumption per mile. Similar differences between 

oil consumption and GHG would apply to electric vehicles, hybrid electric vehicles, and biofuel-powered 

vehicles. 

NHTSA notes that the purpose of EPCA/EISA is not merely to curb petroleum use – it is more 

generally to secure energy independence, which can be achieved by reducing petroleum use. The value of 

incentivizing natural gas, electric vehicles, biofuels, hydrogen, or other alt fuel vehicles for energy 

independence is limited to the extent that the alternative fuels may be imported. 

In recent rulemakings for light-duty vehicles, EPA and NHTSA have followed the light-duty 

specific statutory provision that treats one gallon of alternative fuel as equivalent to 0.15 gallons of 

gasoline. Following that precedent in this heavy duty rule would mean that, for example, a natural gas 

powered truck would have attributed to it 20 percent less CO2 emissions than a comparable diesel 

powered truck, but 85 percent less fuel consumption. Engine manufacturers with a relatively large share 

of alternative-fuel products would likely have an easier time complying with NHTSAs average fuel 

economy standard than EPAs GHG standard. Similarly, engine manufacturers with a relatively small 

share of alternative-fuel products would have a relatively easier time complying with EPA’s CO2 

standard than with NHTSA’s fuel economy standard. In that way, the rule would not differ from the light 

duty vehicle rules. 

Instead, in this rule, EPA and NHTSA are finalizing identical rules. Fuel consumption for 

alternatively-powered vehicles will be calculated according to their CO2 emissions. In that way, there 

will be a one-to-one relationship between fuel economy and GHG emissions for all vehicles. To the 

extent that this rule relies upon reduced petroleum consumption specifically to promote the goals of 

EPCA/EISA, there will be a one-to-one relationship between this reduction and greenhouse gas 

emissions, by design, whether or not that relationship accurately reflects those vehicles’ reduced 

petroleum consumption and GHG emissions for all vehicles. In addition to the significant harmonization 

benefits noted above, this has the advantage of reducing some of the paperwork and compliance burden 

this rule will impose on the truck manufacturers. On the other hand, it has the disadvantage of 

discouraging some cost-effective means of reducing petroleum consumption by trucks, and the 

accompanying energy security costs. By attributing to natural gas engines only 20 percent less fuel 

consumption than comparable diesel engines, because they emit 20 percent less CO2, rather than 

attributing to them a much larger percentage reduction in fuel consumption, because they use no 

petroleum, this uniform rulemaking does not incentivize technologies that reduce consumption of 

petroleum-based fuels. 

Agencies are considering for future rulemakings writing harmonized standards in a way that 

also accurately reflect the true fuel consumption and greenhouse gas emissions. Under such standards, 

any given vehicle might “over comply” with the fuel economy standard, but might “under comply” with 

the CO2 standard. Therefore, in meeting the fleet-wide requirements, a manufacturer would need to 

meet both standards using all available options, such as credit trading and technology mix. Allowing for 

two distinct standards may enable manufacturers to achieve the twin goals of reducing greenhouse gas 

emissions and decreasing consumption of petroleum-based fuels in the most cost-effective manner. 

Comment [A5]: Commenters note that The 

Energy Blueprint and the President’s Energy Speech 

at Georgetown in March both call for NGVs as a 

means of promoting energy security. The Blueprint 

also calls for encouraging development of NG 

production in other countries, to increase our energy 

security by reducing global petroleum demand. 

Commenters also note that Natural gas imports from 

countries other than Canada and Mexico account for 

less than 2% of consumption. 

Comment [A6]: Interagency commenters believe 

this edit is incorrect. There will be a one-to-one 

relationship between GHG and fuel economy. The 

“To the extent that ...” modifier is incorrect. The 

relationship is one-to-one regardless of the goals of 

the legislation or the agencies.