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EPA and NHTSA Response to June 17, 2015 Verbal 

Interagency Comments on Preamble Section IX Rebound -

HDV Phase 2 NPRM

Agencies	Responses:		In	response	to	E.O	12866	comments,	the	agencies	will	incorporate	

the	text	changes	which	are	shown	in	red	type,	below.

(3) How the Agencies Estimated the HDV Rebound Effect for this Proposal

(a) Values Used in the Phase 1 Analysis

At the time the agencies conducted their analysis of the Phase 1 fuel efficiency and GHG 

emissions standards, the only evidence on the HDV rebound effect were the previously described 

studies from CSI and the Volpe Center.1 On the basis of this evidence and the agencies’ 

judgement, the agencies chose rebound effects of 15 percent for vocational vehicles and 5 

percent for combination tractors, both of which were toward the lower end of the range of values 

from these studies. The agencies found no evidence on the rebound effect for HD pickup trucks 

and vans, but concluded it would be inappropriate to use the values selected for vocational 

vehicles or combination tractors for those vehicles. Because the usage patterns of HD pickup 

trucks and vans can more closely resemble those of large light-duty vehicles, the agencies used 

our judgement to select the 10 percent rebound effect we had employed in our most recent lightduty rulemaking to analyze the Phase 1 standards for 2b/3 vehicles.

(b) How the Agencies Analyzed VMT Rebound in this Proposal

After considering the new evidence that has become available since the HD Phase 1 final 

rule, the agencies elected to continue using the rebound effect estimates we used previously in 

 

1 The Gately study was also available, however, the agencies were not aware of the work at the time.
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the HD Phase 1 rule in our analysis of Phase 2 proposed standards. In arriving at this decision, 

the agencies considered the shortcomings and limitations of the newly-available studies 

described previously, particularly the limited applicability of the two published studies using 

data from European nations to the U.S. context. After weighing these attributes of the more 

recent studies, the agencies concluded that we had insufficient evidence to justify revising the 

rebound effect values that were used in the Phase 1 analysis.

In our assessment, we do not differentiate between short-run and long-run rebound 

effects, although these effects may differ. The vocational and combination truck estimates are 

based on the Volpe Center analysis presented in the HD Phase 1 rule and the case study from 

CSI. As with the HD Phase 1 rule, we did not find any literature specifically examining the HD 

pickup and truck sector. Since these vehicles are used for very different purposes than 

combination tractors and vocational vehicles, and they are more similar in use to large light-duty

vehicles, we have chosen the light-duty rebound effect of 10 percent used in the final rule 

establishing fuel economy and GHG standards for MYs 2017-2025 light-duty vehicles in our 

analysis of HD pickup trucks and vans. 

While for this proposal, the agencies have selected to use these rebound effect values of 

5% for combination tractors, 10% for heavy duty pickup trucks and vans and 15% for vocational 

vehicles, we acknowledge the literature shows a wide range of rebound effect estimates. 

Therefore, we will review and consider revising these estimates in the final rule, taking into 

consideration all available data and analysis, including submissions from public commenters and 

new research on the rebound effect. 

...