Literature Review of U*S* Consumer
Acceptance of New Personally Owned
Light Duty Plug-in Electric Vehicles

Response to Peer Review

SEPA

United States
Environmental Protection
Agency



BERKELEY LAB


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Literature Review of U*S* Consumer
Acceptance of New Personally Owned
Light Duty Plug-in Electric Vehicles

Response to Peer Review

This technical report does not necessarily represent final EPA decisions
or positions. It is intended to present technical analysis of issues using
data that are currently available. The purpose in the release of such
reports is to facilitate the exchange of technical information and to
inform the public of technical developments.

Assessment and Standards Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency

and

Energy Technologies Area
Lawrence Berkeley National Laboratory

NOTICE

4>EPA

United States
Environmental Protection
Agency

EPA-420-R-23-901
January 2023

BERKELEY LAB


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1. INTRODUCTION

1.1	Description of Report

In collaboration with Lawrence Berkeley National Laboratory, the Environmental Protection Agency
drafted the report "Literature Review of U.S. Consumer Acceptance of New Personally Owned Light Duty
Plug-in Electric Vehicles" (aka, the Draft Literature Review Report). The primary objective of the Draft
Literature Review Report was to provide a current and comprehensive summary of the scientific
literature regarding consumer acceptance of light duty (LD) plug-in electric vehicles (PEVs) among
private U.S. consumers. The scope of the report included retrospective, prospective, empirical, and
theoretical studies. Scope was also limited to recent (i.e., primarily 2016 and later), peer-reviewed
studies with relevance to the purchase decisions of private U.S. light duty vehicle (LDV) consumers. The
draft report described how PEV acceptance is defined, elicited, observed, and/or measured; the
multifaceted nature and current state of PEV acceptance in the United States among private LDV
consumers; and the attributes of individuals, vehicles, and the systems (i.e., physical, social, and
economic) that enable and stand in the way of PEV acceptance. Another important objective of the
report was to develop an organizing framework that supports actionable insights for a general audience.

In short, the Draft Literature Review Report summarized the current scientific literature regarding 1) the
state of consumer acceptance of LD PEVs, 2) how consumers become aware of PEVs and progress to PEV
adoption, and 3) the obstacles and enablers that hinder and facilitate LD PEV acceptance. The peer
review was intended to evaluate how accurately and completely the draft literature review represents
the current scientific literature regarding LD PEV acceptance, as well as assess the framework used to
organize and interpret the literature. Peer reviewers' comments were thoroughly reviewed by the co-
authors of the Draft Literature Review and incorporated into the final report. The final "Literature
Review of U.S. Consumer Acceptance of New Personally Owned Light Duty Plug-in Electric Vehicles"
(aka, the Final Literature Review Report) is available in EPA's Science Inventory as Publication Number
EPA-420-R-23-900.

1.2	Description of Peer Review Process

EPA's peer review guidelines specify that all influential scientific and technical work products shall
undergo independent peer review per specific agency protocols. To assure the use of the highest quality
science in its predictive assessments, under contract with the EPA, ICF conducted an independent peer
review of the Draft Literature Review Report in accordance with provisions of EPA's Science and
Technology Policy Council Peer Review Handbook, 4th Ed., which can be found at
https://www.epa.gov/osa/peer-review-handbook-4th-edition-2015.

ICF identified three independent subject matter experts, facilitated each expert's review and comments
on the Draft Literature Review Report, and prepared the report "Literature Review of U.S. Consumer
Acceptance of New Personally Owned Light Duty Plug-in Electric Vehicles: Peer Review Report" (aka, the
Peer Review Report). The Peer Review Report contains significantly more detail regarding the peer
review process, ICF's role, verbatim peer reviewer comments, and summaries The Peer Review Report is
Publication Number EPA-420-R-23-003 in the EPA's Science Inventory.

1.3	Peer Reviewers

Three exceptionally well qualified peer reviewers agreed to review and provide comments on the Draft
Literature Review Report. The peer reviewers, in alphabetical order, were as follows:

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Sanya Carley
Indiana University
107 South Indiana Ave
Bloomington, IN 47405:

520-621-0117
scarlev(a)indiana.edu

Michael Maness
University of South Florida
4202 East Fowler Ave
Tampa, FL 33620
813-974-6144
manessm@usf.edu

GilTal

University of California, Davis
1 Shields Ave
Davis, CA 9561
530-754-9230
gtal(a)ucdavis.edu

Reviewers' curricula vitae and completed conflict of interest forms are included in the Peer Review
Report prepared by ICF and available as Publication Number EPA-420-R-22-022 in the EPA's Science
Inventory.

1.4 Charge Questions and Peer Reviewer Comments

Four charge questions defined the scope of the peer review. Reviewers responded to the charge
questions as well as overall and section specific comments. The charge questions were as follows:

1.	Does the report provide a current, comprehensive, clear, and accurate summary of the scientific
literature regarding consumer acceptance of LD PEVs among private consumers of LD vehicles?

2.	Does the report miss any relevant literature?

3.	Is the organizing framework appropriate to satisfy the following objectives according to the
current scientific literature?

•	Capture the range of LD PEV acceptance issues among LD vehicle consumers.

•	Identify what motivates LD PEV acceptance among prospective LD consumers and what
stands in their way.

4.	Does the synthesis contained in the report provide reasonable, defensible conclusions that
accurately reflect the body of scientific literature regarding consumer acceptance of LD PEVs
among private consumers of LD vehicles?

Reviewers' verbatim response to charge questions, overall comments, and section specific comments
are documented in the Peer Review Report prepared by ICF which is available as Publication Number

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EPA-420-R-23-003 in the EPA's Science Inventory. Verbatim comments also appear below in Co-Authors'
Response to Peer Review

2. CO-AUTHORS' RESPONSE TO PEER REVIEWERS' COMMENTS

In the following three tables, the co-authors of the draft "Literature Review of U.S. Consumer
Acceptance of New Personally Owned Light Duty Plug-in Electric Vehicles" (aka, Draft Literature Review
Report) respond individually to all of the comments provided by each of the reviewers. The co-authors
also clearly indicate changes made to the Draft Literature Review Report in response to each peer
reviewer comment. The co-authors also indicate where those changes were made. See Sections 2.1
(Tables 1 - 4), 2.2 (Table 5 - 7), and 2.3 (Tables 8-9) for co-authors' responses to charge questions,
overall comments, and section-specific comments, respectively.

In every instance, the co-authors found the reviewers comments to be valuable, leading to revisions that
improved the quality of the Final Literature Review Report. Even when the comment did not lead to
revisions, the reviewers' comments clarified for the co-authors how readers are likely to interpret and
utilize the Final Literature Review Report. Thus, the coauthors are sincerely grateful for all the reviewers'
thoughtful comments, excellent questions, expert insights, and impressive attention to detail.

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2.1 Co-Authors' Response to Reviewers' Comments by Charge Question

Table 1. Charge question #1: Does the report provide a current, comprehensive, clear, and accurate
summary of the scientific literature regarding ^consumer acceptance of LD PEVs among private
consumers of LD vehicles?

Reviewer

Reviewer Comment

Response

Addressed
in:

Dr. Carley

1 think that the report does an excellent
job of providing a comprehensive and
complete picture of the literature. 1 have
a few minor suggestions for other
studies that the authors could fold into
the analysis in my section specific
comments below, though the authors
may deem some of them unnecessary or
too tangential to their focus, which is
fine.

We reviewed the additional section-
specific citations suggested by Dr.
Carley and incorporated those we
deemed useful and appropriate in the
revised report.

Several
sections

Dr. Tal

The return of the electric cars in the last
decade, shifting from "experimental
vehicles" used by very few to a product
used by millions, created new interest
among the scientific community. Many
scientific studies and almost as many
reviews have been published in the last
decade, but this one is the most
comprehensive and the most up-to-date
work that can be used by researchers
and policymakers. The most important
challenge that the authors have tackled
successfully is keeping it relevant and
condensing the messages in a coherent
way. The motivation behind the report,
though not stated, is not only to
describe the current market of PEVs and
how they are being used, but to
understand the circumstances (i.e.
causality mechanisms) that created this
market and what can be expected in the
future given different scenarios or
policies.

The motivation to "understand the
circumstances ... that created this
market" is out of scope. It was not our
intention to explain why a PEV market
has emerged. Second, the motivation
to "understand ... what can be
expected in the future given different
scenarios or policies" is also out of
scope. Our scope did not include
projection-type models nor did we
evaluate or craft scenarios or assess
specific policies. Our intention was to
focus on what constitutes PEV
acceptance, namely how it is defined,
elicited, observed, and/or measured;
the multifaceted nature and current
state of PEV acceptance in the United
States among new personally owned
LDV consumers; and the attributes of
individuals, vehicles, and the systems
(i.e., physical, social, and economic)
that enable and stand in the way of
PEV acceptance. In the introduction of
this report, we have expanded the
description of the report's scope to
address the ambiguity suggested by
Dr. Tal's comments.

1.1

Dr. Maness

Yes. It touches on most of the relevant
areas of research.

We thank Dr. Maness for assessing the
comprehensiveness of the report.

N/A

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Table 2. Charge question #2: Does the report miss any relevant literature?

Reviewer

Reviewer Comment

Response

Addressed
in:

Dr. Carley

1 do wonder whether the adherence to 2016
studies or later might lead the authors to
overlook any important or foundational
analyses? 1 don't have any specific studies in
mind here though, 1 just wanted to flag this in
the event that there are any foundational
pieces that were published before 2016 that
could help advance the narrative?

1 will also note that there are two specific
scholars (among many) who 1 consider to be
leaders on EV scholarship and who are
pushing the field in important ways: Alan
Jenn and John Axsen. 1 see several of their
studies referenced in the piece and, although
1 have no specific additional studies of theirs
in mind, the authors may want to review
both of their work one more time to ensure
that they captured anything new or cutting
edge that they have published recently. One
example is this recent piece by Jenn:
https://itspubs.ucdavis.edu/publication_deta
il.php?id=3089.

To focus on the current state of research,
we prioritized research published in 2016
and later. We believe that seminal works
published before 2016 underpin many of
the studies that we have included and need
not be reviewed and cited in this report.
When papers published before 2016 appear
to be the clearest or only discussion of a
particular topic, we reviewed and included
those studies.

N/A

Dr. Tal

A short but important topic is missing from
this review, most likely because of the small
numbers of studies that focus on it. The
adoption of new vehicles for the first time
only covers a smaller share of the behavioral
change that needs to happen on the way to
clean electric transportation. Most Americans
may purchase their first electric car as a used
car while other households will purchase
their second or third PEV and will own a fleet
of two or three PEVs. In some cases, EV
owners may go back to driving ICEV (Internal
Combustion Engine Vehicles). 1 believe it will
be important to review the total numbers of
new versus used car sales in the US. It is
important to review the limited literature on
the topic, including fleet turnover models
that are not directly exploring behavior.

We agree with Dr. Tal that used PEV
purchase, PEV repurchase, and PEV
retention are important topics. As noted by
Dr. Tal, the used PEV market is small and
nascent, as are these fields of study. As a
result, we chose to focus only on new PEVs.
We have similarly chosen to exclude other
ancillary topics related to PEV acceptance,
which we enumerate in the introduction
(Section 1.1).

1.1

Dr.

Maness

Yes. There are some review papers that are
not mentioned that would help in
summarizing the attributes consumers
consider. There was some missing work on
incentives and their effectiveness.

Dr. Maness suggested additional citations in
his section-specific comments. We reviewed
his suggestions and added those deemed
appropriate. Regarding incentives, the
original draft addressed incentives in
sections 4.3 and 4.4, including a number of
citations. In response to Dr. Maness's
suggestions, we now include several.

Multiple
sections

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Table 3. Charge question #3: Is the organizing framework appropriate to satisfy the following
objectives according to the current scientific literature?:

•	Capture the range of LD PEV acceptance issues among LD vehicle consumers.

•	Identify what motivates LD PEV acceptance among prospective LD consumers and what stands in

their way.

Reviewer

Reviewer Comment

Response

Addressed
in:

Dr. Carley

1 really like the 4-A framework and think that
it is highly effective for this piece and will
hopefully be helpful for future scholarship as
well!

We thank Dr. Carley for her assessment of
the framework and similarly hope that it
will inform future scholarship.

N/A

Dr. Tal

The review is based on a four steps model,
suggested as the "stages of consumer
acceptance", which helps categorize the
reviewed papers into one of the four stage
categories. The first stage is awareness: the
knowledge of PEV existence, availability, and
technical characteristics. The second stage is
access: the PEVs actual availability, including
the ability to fulfill driving needs and charging
availability. The third stage is approval: the
willingness to include a PEV in the
consumer's next vehicle choice set, and
Finally, the last stage is adoption: the
revealed behavior, in this case, limited to
first-time purchase or lease of a PEV. This
model is very useful, and 1 believe it can be
used even more in the Synthesis part of the
report. The suggested framework is based on
the decision process of an individual or a
household buying or leasing their first PEV
but does not directly address the impact of
environmental factors, including social
effects.

This framework also does not directly address
the question of causality but the follow-up
questions in the report call for causality
investigation: *What is the current state of
LD PEV acceptance in the United States
among personal-use consumers at each stage
of acceptance? *How does a U.S. consumer,
community, or the nation, move through the
stages of PEV acceptance? *What enables
their progression at each stage of
acceptance? *What stands in their way at
each stage of acceptance?

We are glad that Dr. Tal found the 4-A
framework useful. We appreciate his
suggestion to include supplemental
information on the methodologies of the
cited studies. While a large undertaking, we
agree that this adds utility to the report. In
line with his suggestion, we now include an
appendix table that notes the analytical
methods, scope, sample size, and type of
findings reported for the majority of our
cited articles and reports. We do not
include foundational methods papers,
websites, news articles, or other sources
where the format of the information is not
suited to the table's fields. Regarding the
issues of correlation versus causality, we
have revisited the language we use in
discussing studies and use phrasing like
"associated with" or "correlated with" in
cases where causality is less conclusively
proven. Furthermore, we note that a
primary goal of this report was the
elucidation of the 4-A framework itself. We
hope that others will continue to populate
this framework with up-to-date research
and currently out-of-scope topics. Finally,
and as technical clarification only, we do
not use the 4-A framework to "categorize
reviewed papers". We use the framework
to categorize findings from reviewed
papers, as some studies speak to more than
one stage of acceptance.

Multiple
sections;
Appendix A

Table 3 continued on next page...

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Continuation of Table 3. Charge Question #3:

Reviewer

Reviewer Comment

Response

Addressed
in:

Dr. Tal

(continued) 1 believe that it will be important
to acknowledge the type of modeling of the
reviewed literature related to causality. Many
of the reviewed studies are only presenting
descriptive statistics of the explored topic
while other studies have used cross-sectional
designs to establish a statistical association
between awareness, access, approval, and
adoption (usually controlling for socio-
demographic characteristics or using those as
explanatory variables). The Cross-sectional
designs do not establish whether the cause
precedes the effect, for example, does public
charging infrastructure cause a market
growth? Is it the number of new EVs that
trigger charging installation? Or is there a
third instigation, such as local policy, that
generates both charging infrastructure and
EV market growth? By falling short on the
criteria of time-order and non-spuriousness,
most studies leave open the possibility of
false causality or one that stems from self-
selection.

Causality in social research that is focused on
adoption of new technologies can be
explored in many ways and it may be useful
to add some discussion on the topic where
applicable. 1 suggest exploring the following
methods (Including but not limited to): direct
questioning, instrumental variables models,
statistical control by including knowledge
attitudes etc., propensity score, sample
selection models, longitudinal designs, and
structural equations models.

This type of analysis will be very important
for studies that look at the impact of any
factor directly on adoption such as the
impact of vehicle sales, awareness, access,
and charging infrastructure.

(see above)

(see above)

Table 3 continued on next page...

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Continuation of Table 3. Charge Question #3:

Reviewer

Reviewer Comment

Response

Addressed
in:

Dr.

Maness

Yes. The framework is easy to understand
and simplified. 1 think there needs to be a
little more differentiation between adoption
and approval.

We agree with Dr. Maness that there can be
overlap between stages of the 4-A
framework. The 4-A framework is a stylized,
linear representation of a process that is in
fact nonlinear and multidimensional. As a
result, differentiation between stages can
be difficult or subjective in some cases.
Nevertheless, we discretize and linearize
the stages to simplify complexity primarily
to meet the needs of policy makers. Those
needs often include structures and content
that are parsimonious, informative,
actionable, and measurable. Regarding
adoption and approval specifically, the
definitions are delineated by the clearly
observable actions associated with
adoption (e.g., purchase, new vehicle
registration). Enablers and obstacles are
less clear, as noted by the reviewer. In the
report, we recognize enablers and obstacles
as relevant to approval or adoption based
on the dependent variable in the studies
reviewed.

N/A

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Table 4. Charge question #4: Does the synthesis contained in the report provide reasonable,
defensible conclusions that accurately reflect the body of scientific literature regarding consumer
acceptance of LP PEVs among private consumers of LP vehicles?	

Reviewer

Reviewer Comment

Response

Addressed
in:

Dr. Carley

1 think that the synthesis is effective and
does a nice job of summarizing the literature.
1 offer a few additional suggestions in my
notes below of other topics that the authors
may consider weaving into the analysis as
well, such as a discussion of what is missing
from the literature but important to know.

We have reviewed the additional
section-specific citations that
were suggested by Dr. Carley and
incorporated those we deemed
useful and appropriate into the
report.

Multiple
sections

Dr. Tal

Another methodological concern is the
quality and the relevancy of the data used
for each study. This report is based on mostly
papers published after 2016 which, based on
academic timelines, uses data collected
between 2010-2019 and reflect the
knowledge awareness and revealed behavior
of this time frame. The rapid change in PEV
technology and, in some cases, the market
growth makes it very difficult to study the
topic. In many cases, researchers are
drawing conclusions about the future of PEVs
in a manner analogous to studying current
smartphones based on a survey of the first
iPhone. In both the case of the iPhone and
electric vehicles in early stages, both the
technology and type of people who buy the
technology is very different from the next
generation of buyers. 1 believe that it will be
very useful to add a review table of the type
of data collected (stated preference,
revealed behavior, new car buyers only, all
population etc.), the time the data was
collected, and the sample frame. 1 think it
will be critically important for studies who
used revealed behavior. When applicable, it
may be useful to distinguish between studies
who focus on current behavior and studies
that are trying to use forecasting methods or
to look at changes over time. 1 think that the
authors should not be shy of hinting on the
relevancy of different papers for future
forecasting and policy.

Within the report, we
intentionally limited the
presentation of data specific
information, such as reference
time periods, regions, and
populations, to maintain fluidity
and readability of the text.
However, we agree with Dr. Tal
regarding the importance of this
information. Thus, we now
include an appendix table that
notes the analytical methods,
scope, sample size, and type of
findings reported for the majority
of our cited articles and reports.
We do not include foundational
methods papers, websites, news
articles, or other sources where
the format of the information is
not suited to the table's fields.

Appendix A

Dr. Maness

Yes, mostly. Some paragraphs and
conclusions made sound somewhat
anecdotal - which while 1 believe they are
accurate, additional citations would
strengthen the perception of accuracy. 1 have
not noted every instance (but 1 identify a few
in the comments, e.g. p.21).

In accordance with Dr. Maness's
comment, we added citations
where suggested and elsewhere
to "strengthen the perception of
accuracy."

Multiple
sections

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2.2 Co-Author's Response to Reviewers' Overall Comments
Table 5. Overall Comments from Dr. Carley	

Reviewer Comment

Response

The authors recognize that EV sales/acceptance vary by
geography and socioeconomic group, but might it be worth
diving into the disparities covered to date in the literature?
While the authors discuss how several studies have found EV
consumers to be higher income and/or more educated, there is
no discussion of what we have learned from studies that
evaluate the distribution of government EV subsidies. See, e.g.,
Borenstein, S. and L W. Davis (2016). "The distributional effects
of U. S. clean energy tax credits." Tax Policy and the Economy30:
191-234. This may be outside of the scope of the study, since it
is focused on tax incentives rather than consumer preferences
and adoption, but I think that it is at least relevant and
revealing. I really appreciate how well the report is organized.
And I love Figure 10. It's such a nice way to summarize
everything into a single figure. Fleet drivers are also a form of
"test drivers" and there are many, many fleet drivers out there. I
think that the piece does a nice job of highlighting that it is not
just the actual benefits and barriers to acceptance that matter,
but it is also the perceptions of these benefits and barriers, and
that perceptions often may not match reality (as an aside, I have
work with coauthors that we haven't published that shows that,
over time, perceptions and reality have started to converge, but
that misperceptions still persist; it's possible that others have
found similarly, though I am aware of no specific study). This
point is made in several sub-sections, but I wonder if it could be
pulled out as a major theme that is prevalent across the full 4-A
framework? Do the authors want to discuss what's
understudied in the literature? What is the literature not
addressing? Possibilities: -Local level dynamics? What happens
on the ground to make EVs a priority in local communities?
How to make sure that dealerships have options, fleets are
converted, EV programs are available for underserved
populations, etc.? -How policies fail to encourage EV purchases:
there are no teeth on ZEV policies. How to make them effective?
(Note that in our earlier work, we find that early EV sales do not
align with ZEV policies (Clark-Sutton, K., Siddiki, S., Carley, S.,
Wanner, C., Rupp, J., Graham, J.D. 2016. Plug-in electric vehicle
readiness: Rating cities in the United States. The Electricity
Journal29(l): 30-40) and that EV and GHG policies are highly
misaligned (Carley, S., Zirogiannis, N., Duncan, D., Siddiki, S.,
Graham, J. D. 2019. Overcoming the shortcomings of U.S. plug-
in electric vehicle policies. Renewable and Sustainable Energy
Reviewsll3:1-10)). -How to extend access to EVs and charging
station for underserved populations? -How supply constraints
affect consumer acceptance? If the authors want to discuss the
changing EV policy landscape, they could use the NC Clean
Energy Technology Center's quarterly reports, such as the most
recent one.

We appreciate Dr. Carley's detailed suggestions
regarding the nuances of consumer acceptance of
PEVs and related topics. While we agree that these
topics are important and interesting, they are out of
scope for this project for several carefully considered
reasons. Most importantly, we need to manage the
scope of this work. In addition, some topics are
substantial in importance, content, or complexity that
is more than sufficient to justify reports of their own.
For example, topics related to disparities, distribution
of subsidies, and underserved populations touch on
issues of equity, which given the scientific literature
on this topic and its importance, is deserving of more
complete and nuanced treatment than could be
achieved in this literature review. Similarly, we
acknowledge that the literature on the design and
effectiveness of policy interventions is rich. We
nevertheless chose to curtail the presentation of this
literature since a comparative analysis of policy and
policy design warrants an in-depth and technical
assessment of policy attributes not indicated in our
stated objectives. This choice perhaps has the added
benefit of a more expansive and perhaps more
balanced presentation of acceptance enablers than
drilling down into policy particulars would allow.
Likewise, we acknowledge the importance of local
level actions and dynamics as well as local level
heterogeneity, but we do not delve into local level
topics to manage the scale of the report. In the report,
we do note the considerable efforts of other
researchers in capturing local level considerations and
refer readers to those studies and reviews. Lastly, for
some topics, the literature was nascent, emerging, or
relatively light. Current issues, such as supply
constraints, used PEV markets, and PEV repurchase,
are currently being analyzed by many researchers. In
several years' time, the findings from these studies
may be appropriate to consider in the context of the
4-A framework. Other issues of interest, as noted by
Dr. Carley, were absent or arguably received
insufficient treatment in the literature. Because our
intent was to comprehensively present current
findings of the scientific literature regarding U.S.
consumer acceptance of new light duty plug-in electric
vehicles and to do so in a cohesive and ingestible
manner, we leave it to our readers and other
researchers to identify gaps in the literature.

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Table 6. Overall Comments from Dr. Tal

Reviewer Comment

Response

1 believe that the report is very good in its current stage, but if
the authors would like to address some of my comments, it may
be best to add subsections to some of the existing structure in
the synthesizing part instead of rewriting the report. The current
structure is very clear and useful and very difficult to rearrange.
Adding sub sections and appendix tables on causality data
sources and other sources will help the reader gauge the quality
and relevancy of the different studies.

We appreciate Dr. Tal's comments on our work and
suggestions for additions. We agree that restructuring
the report is unnecessary. We do, however, add
subsection headings, rephrase to distinguish
associations and correlations from causality, and add
an appendix documenting data, methodologies, and
other information to assist readers in gauging the
quality and relevance of each study.

Table 7. Overall Comments from Dr. Maness

Reviewer Comment

Response

The chapter breakdown makes sense and is generally helpful. 1
thought there needs to be more organization in Chapter 2 (see
specific comments) and that some sections of Chapters 3-6
could have subsections for readers to find their relevant areas /
get a quick summarized understanding. Generally the
enablers/obstacles to adoption are described as being the same
between all stages, but 1 think this misses the point of having
distinct acceptance aspects. The sections delve more into this
with specificity (so the sections themselves are actually
distinctively different). But upon initial reading, they end up
sounding very similar when you read the first paragraph or two.
The method of exploring the literature could use some
additional explanation. It is good that the thoroughness of the
literature search is explicitly mentioned, but perhaps the base
papers that were used to start the discussion could be
mentioned and the search terms used.

Dr. Maness provided detailed comments throughout
the draft, which we addressed through the addition of
subsection headers, rewording and reorganizing text,
clarifying stages of acceptance, and further
differentiating stage-specific enablers and obstacles of
acceptance. In addition, we have provided more detail
for our search and selection approach to identifying
literature to review. This includes a search terms used
to collect our original database of potential literature.

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2.3 Co-Author's Response to Reviewers' Section Specific Comments

Table 8. Reviewer Comments by Report Section: Dr. Carley

Review Comments from Dr. Carley

Section

Reviewer Comment

Response

l.l

The Alliance for Automotive Innovation keeps an ongoing web
dashboard on EV sales. You mayconsider updating your
numbers through 2021 with these data?
https://www.autosinnovate.org/initiatives/energy-and-
environment/electric-driveand

https://www.autosinnovate.org/resources/electric-vehicle-
sales-dashboard. If you also want international data, you could
use this: Bloomberg New Energy Finance, "Global Electric
Vehicle Outlook: Executive Summary" (2021),
https://about.bnef.com/electric-vehicle-outlook/.

In accordance with Dr. Carley's
suggestion, we added actual annual 2021
PEV sales statistics and actual PEVs sales
statistics for 2022 through May 2022 (i.e.
most recent data available via the Alliance
for Automotive Innovation Electric Vehicle
Sales Dashboard on the access date of
September 29, 2022).

1.2

This comment may be an annoying technicality, so feel free to
ignore it. HOV lane access can actually be monetized. 1 believe
that one study found that in CA, the premium on the secondary
market for hybrids with HOV lane access was about $5,000.
Pretty impressive! Other possible non-financial benefits/barriers
may include appreciation of the acceleration, pride in being an
early technology pioneer, and disapproval of the look and other
vehicle attributes associated with the EV.

We differentiate between financial and
non-financial interventions (i.e. actions
taken by non-consumers to motivate
consumers) versus monetizable and non-
monetizable interventions. While HOV
access can be monetized as Dr. Carley
correctly points out, it is not clearly a
financial incentive like a tax credit or
rebate is, for example, which we
characterize as financial. We also
differentiate between interventions and
the types of benefits cited by Dr. Carley
that derive from vehicle attributes (e.g.,
acceleration) or consumer characteristics
(e.g., tech-forward) and attitudes (e.g.,
pride).

1.3

1 really like your 4-A framework! Well done.1.3, page 5, under
"Adoption": some studies argue that test driving an EV leads
one from approval to adoption. Might it be worth featuring this
topic, even briefly, in this section (although 1 do see mention of
it at the end of section 1.4)?

To capture this insight, we added text to
Section 1.3 in the description of adoption.

1.4

You may consider spiffing up Figure 2?

We have revised Figure 2 to demonstrate
more clearly the centrality of consumers,
the diversity of consumers, the myriad
choices among vehicles, and the primary
systems (i.e., markets, governments,
physical infrastructure, and social
networks) that all together create
consumers' decision contexts.

12


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Continuation of Table 8. Reviewer Comments by Report Section: Dr. Carley

Section

Reviewer Comment

Response

1.4

The main finding is as follows: "In other words, we found no
evidence in the reviewed literature to suggest anything
innate to consumers or inherent to PEVs that obstructs
acceptance." Based on my own understanding of the
literature, 1 agree with the authors that evidence is limited
but 1 think that using "no" before evidence might be a bit
strong. 1 can think of two counter examples: first, people
are limited by their own understanding of EVs (e.g., how far
they drive on a single charge); second, there is some
evidence that people face cognitive barriers to assessing
the value of an EV relative to an ICE (see, e.g., a study on
how providing monthly cost of ownership figures could lead
to different rates of approval for EVs:
https://www.sciencedirect.com/science/article/pii/S09658
56414002912).

We intended to convey that there is no
evidence of anything that is irremediable or
immutable within consumers that would
prohibit acceptance. The phrase "innate to"
appears to be insufficient. Thus, we have
changed it to "immutable within" and added
the modifier "irremediably" to "obstructs."

1.1

Sorry if 1 missed this: do you want to acknowledge that this
study focuses primarily on the U.S.? If the intent is not to
focus on the U.S., on the other hand, then do you want to
pull in more data and examples from other countries (e.g.,
what does the early adopter look like in the U.S. vs.
China?)?

To address this and other comments related to
the scope of this review, we have expanded
the introduction to include more explicit
statement of what is included and excluded
from this review as well as our rationale for
these choices. Throughout, we have repeated
language related to the scope of the review to
aid our readers. Regarding this particular
question, we have almost exclusively included
only studies of U.S. consumers. We highlight
this focus in the report title.

2.1

Part of awareness is awareness not just of an EV itself but
also of its attributes, costs, and features, right? Someone
could know a decent amount about an EV but still have
misunderstandings about its costs or GHG savings, as just
two examples.

Dr. Carley's comment is correct. The report
makes clear that awareness is not binary, and
therefore, allows for the complexity
exemplified by Dr. Carley's example.

2.5

On the topic of economic aspects: note that this depends
on what price they must pay for the car, which is influenced
by location, dealership, loan/cash payment, a government
incentives. Here you can note also that not everyone can
take advantage of those government incentives when they,
for example, do not pay significant taxes.

Section 2 is intended to define consumers,
decision process, and decision contexts as well
as introduce key topics. We delve more deeply
into topics such as vehicle price, location,
dealerships, loans versus cash, and
government incentives in Sections 3, 4, 5, and
6. Regarding access to federal tax credits, we
note this obstacle in section 4.4.

2.5

On the topic of safety: note that some perceive the battery
to be a fire hazard? Although it is not clear to me whether
these attributes, as discussed in the text, are intended to be
actual attributes or perceptions of them?

We address the role of consumer perceptions
in Sections 2.3 and 2.5. We added text to
emphasize this point in Section 2.5. Regarding
safety, consumers value safety, and their
perceptions of safety greatly influence
purchase decisions. Regarding battery fires,
this topic appears in the popular news, but we
did not review any studies that specifically
examined the perception of PEVs or PEV
batteries as fire hazards.

13


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Continuation of Table 8. Reviewer Comments by Report Section: Dr. Carley

Section

Reviewer Comment

Response

2.6.1

See Dumortier, J., Siddiki, S., Carley, S., Cisney, J., Krause, R.,
Lane, B., Rupp, J., Graham, J. 2015. Effects of providing total
cost of ownership information on consumers' intent to
purchase a hybrid or plug-in electric vehicle. Transportation
Research Part A: Policy and Practice 72: 71-86.This study
finds that the manner in which total cost of ownership is
presented to a potential car buyer has big implications for
their interest in an EV.

We added the citation suggested by Dr. Carley
to our review in Section 2.6.1.

2.6.1

Add ability to pay in cash vs. having to take on a loan? Add
ability to recover expenses through a tax credit?

Section 2 is intended to define consumers,
decision process, and decision contexts as well
as introduce key topics. We do include "a
consumer's personal wealth and income, and
availability and access to credit", which
encompasses Dr. Carley's points. We also
added the phrase "ability to recover expenses
through a tax credit" to section 2.6.1. These
topics in more in Section 4 in our detailed
discussion of access and affordability.

2.6.1

Might you want to note that not every consumer is able to
install a charger at their residence? If they rent, for
example, or own a unit in a multi-family dwelling, they may
not be able to install chargers.

We added a phrase in Section 2.6.1 that
addresses Dr. Carley's question and example.
We also discuss this topic more in Sections 4.4
and 5.3.

2.6.3

See Zambrano-Gutierrez, J., Nicholson-Crotty, S., Carley, S.,
Siddiki, S. 2018. The Role of Public Policy in Technology
Diffusion: The case of Plug-in Electric Vehicles.
Environmental Science & Technology 52(19): 10914-10922,
which finds that support for charging infrastructure is an
important mediating variable for tax incentive
effectiveness.

We added Zambrano-Gutierrez et al (2018) to
this review and provided this example in
Section 2.6.3.

4.2; 6.2

Again, 1 encourage you to update your sales figures with
Alliance for Automotive Innovation Dashboard data
(https://www.autosinnovate.org/resources/electric-
vehicle-sales-dashboard).

We added sales statistics from the Alliance for
Automotive Innovation Electric Vehicle Sales
Dashboard to this review.

4.2.2

1 wonder if there is value in visually comparing charging
stations (as is presented in Figure 4) alongside of EVs sold?

We agree that the ability to easily compare
figures showing BEVs density, density of public
charging stations, and number of PEV and
EVSE incentives is useful. Thus, we have
modified our figures so that all three figures
appear together under Section 2.6 where we
discuss how consumers interact with systems.

14


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Continuation of Table 8. Reviewer Comments by Report Section: Dr. Carley

Section

Section

Section

4.3

On the cost of batteries: Do you want to note that battery
availability is a challenge as well, and specifically the rare
earth minerals that are needed for battery production?
Another set of challenges here are the size and
compatibility of batteries: the batteries are often so large
that they take up valuable cargo space; and the batteries
are rarely (never?) compatible across manufacturers, which
has implications for cost, charging infrastructure, battery
swapping business models, and recyclability/reuse.

We added a footnote that addresses the
issues that Dr. Carley raises.

4.3

Note that the infrastructure bill devotes a fraction of all
charging infrastructure support to underserved
neighborhoods?

We made this addition to the text.

6.3

Paragraph that starts with "Jia and Chen...": you could end
this paragraph by saying "and greater effectiveness of tax
incentives" (citing Zambrano-Gutierrez, J., Nicholson-Crotty,
S., Carley, S., Siddiki, S. 2018. The Role of Public Policy in
Technology Diffusion: The case of Plug-in Electric Vehicles.
Environmental Science & Technology 52(19): 10914-10922).

We made this addition to the text.

7

You note that there is reason for optimism. But optimism
about what? 1 also wonder whether it is better to
emotionally remain neutral about the fate of EVs?

In accordance with Dr. Carley's advice, we
have rephrased this passage.

7

1 find the following passage confusing: "However, current
PEV adopters are currently concentrated in locations with
pro-PEV policies and higher numbers of charging stations.
Indeed, PEV acceptance -awareness, access, and approval
as well as adoption -is higher in favorable locations and
among individuals with favorable characteristics. Note that
we use the word "favorable" to describe locations where
PEV adoption, charging infrastructure, and pro-PEV policies
co-occur. We also use the word "favorable" to describe the
demographic and psychographic characteristics often
associated with current PEV adopters, keeping in mind that
many PEV adopters do not possess these favorable
characteristics and thus favorable characteristics clearly are
not necessary for PEV adoption."

We have cut parts of this passage and
rephrased for clarity.

7.1

On the topic of exposure: Here again 1 think that you could
add awareness through a company's fleet?

We made this addition to the text.

7.4

First full paragraph: Isn't access to charging station
incentives another adoption enabler?

We have retained the original text and believe
that the phrase "incentives (e.g., subsidies,
rebates, and tax credits)" is inclusive of the
charging station incentives mentioned by Dr.
Carley.

7

Change TOC to TCO (total cost of ownership)?

We have corrected this abbreviation in Figure
10. We sincerely appreciate this attention to
detail.

15


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Table 9. Reviewer Comments by Report Section: Dr. Maness

Review Comments from Dr. Maness

Section

Reviewer Comment

Response

General

Would be useful if sections 4.1, 5.1, and 6.1 listed the
metrics similarly to section 3.1

The Adoption chapter has some aspects that seem better
suited for access or approval and vice-versa. A framework
suggest adoption is that ending process where you have
finally fully deliberated and actually took the plunge. Some
of the aspect mentioned help consumer get on the diving
board rather than jump off it.

1 have listed specific comments in the attached word
document. Unless mentioned explicitly, all comments are
assumed to be able to be improved with the tools available
to EPA (mostly time to write/edit, access to journals).

As suggested by Dr. Maness, we now present
the metrics in 4.1, 5.1, and 6.1 as lists.

1.2

1 could not see the full text for "Systems/Context" in the
image.

We have revised the image, re-sized the text,
and made this a static image.

1.5

Statement seems somewhat circular

We have revised this section for clarity.

2

1 found the sections of this part to bounce around much. 1
think a summary/outline paragraph to seeks explain why
each section is here/the flow of the sections would be
helpful

We have included additional introductory text
to frame the following subsections.

2.1

"One such depiction is the five-step consumer purchase
process": This is an existing process? Needs a citation... 1
know at least the 11th edition of "Consumer Behavior:
Building Marketing Strategy" includes this concept... 1 do
not know if a newer edition does.

We have added two citations to seminal work
in this area: Darley, W. K., Blankson, C., &
Luethge, D. J. (2010). Toward an Integrated
Framework for Online Consumer Behavior and
Decision Making Process: A Review.

Psychology & Marketing, 27(2), 94-116. Engel,
J. F., Kollat, D. T., & Blackwell, R. D. (1968).
Consumer Behavior. New York: Holt, Rinehart,
and Winston.

2.1

"Even if consumers are aware of PEVs, there is evidence
that households seeking to replace a vehicle are less likely
to be willing to consider PEVs (i.e., less likely to approve of
PEVs) than those looking to purchase an additional vehicle
(e.g., Higgins, Mohamed, and Ferguson 2017).": The hybrid
household / two-car household hypothesis?

We have added the suggested citations.

2.1

"Common criteria considered under alternative evaluation
include several relating to PEV access, including: vehicle and
model availability at nearby dealerships (access in terms of
geography); vehicle attribute availability (access to utility);
purchase price, financing options, and financial incentives
(access in terms of affordability); and availability of public
charging and/or potential for home charging (access to
infrastructure).": Think this would be nice in a list form

Following Dr. Maness1 suggestion, these
criteria types are now presented as a list.

2.1

"[...] but is happening more via other means)": Can be more
specific, or Is this covered later?

We discuss online sales more in later sections,
but we have also added a footnote here about
online sales.

16


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Continuation of Table 9. Reviewer Comments by Report Section: Dr. Maness

Section

Reviewer Comment

Response

2.2.1

This section does not really seem focused on its title. Most
attention is towards limitations by body type/size.

We believe this section logically defines the
compensatory and noncompensatory
vehicle criteria. We offer body style as a
particularly relevant example of
noncompensatory criteria for PEVs. In
response to Dr. Maness1 comment, we
condense our body style example
somewhat and add additional examples of
compensatory and non-compensatory
criteria.

2.3

1 would generally say the sociodemographics are proxies for
other characteristics (most latent) and constraints. 1 may
suggest stating that there are general characteristics of
consumers and households to make PEV usage easier/harder.
Because of the ease of observations, sociodemographics are
used, but they can be fluid/dynamic... a common policy goal is
to make sociodemographics as irrelevant as possible.

We agree with Dr. Maness1 comments.
While we chose not to address these
comments in the report, we believe his
comments merit a thoughtful response.
First, we believe that the opening
paragraphs of Section 2.3 make sufficiently
clear distinctions between observable and
unobservable characteristics with socio-
demographics and latent characteristics
serving as examples. Second, we have
taken into consideration the fluidity of
consumer characteristics and the ways in
which consumer characteristics make PEV
acceptance more or less likely throughout
our review. Finally, we appreciate Dr.
Maness description of policy objectives.
However, characterizing policy objectives is
out of the scope of this review. Rather, as
stated in Section 1.4 "we seek to
understand how a broad range of actors
and factors facilitate PEV acceptance, and
how to overcome potential obstacles."

2.3.1

Sentence, "Specifically, buyers of high-end BEVs (represented
by the Tesla Model S) differed significantly from buyers of low-
end BEVs (represented by the Nissan Leaf) in terms of gender,
income, education, and age (Hardman and Tal 2016)." When 1
first read the statement, it sounded like an endorsement of
these two vehicle models... Consider starting the statement
with the paper authors or "a study found..." and 1 think you
mean Hardman et al. 2016. There is no 2016 article from these
authors in the reference list. Hardman and Tal 2021 does not
mention a Nissan Leaf.

We have rephrased this sentence for clarity
and switched to the (correct) Hardman et
al. 2016 citation.

17


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Continuation of Table 9. Reviewer Comments by Report Section: Dr. Maness

Section

Reviewer Comment

Response

2.5

"Here we describe some of the key attributes relevant to
vehicle purchase decisions and the vehicle features and
metrics that relate to them."

Consider these two review article on attributes:

•	Liao F, Molin E, van Wee B. Consumer preferences for
electric vehicles: a literature review. Transport Reviews. 2017
May 4;37(3):252-75.

•	Coffman M, Bernstein P, Wee S. Electric vehicles revisited: a
review of factors that affect adoption. Transport Reviews. 2017
Jan 2;37(l):79-93.

We have added the suggested references
in a footnote.

2.5

"[...] engine and related vehicle systems": Suggest to add
electric motors here since it is the PEV's tractive effort source.

We now use the term "electric motor" in
this sentence.

2.6.2

Possible additional source: Adepetu A, Keshav S, Arya V. An
agent-based electric vehicle ecosystem model: San Francisco
case study. Transport Policy. 2016 Feb l;46:109-22.

We have added the suggested reference.

2.6.3

Paragraph 1, Acronym, "EVSE": First mention of this acronym -
please define

We spelled out Electric Vehicle Service
Equipment and added the acronym
parenthetically.

2.6.3

Paragraph 2, Word, "number": Quantity? Supply?

We removed the word "number" from this
sentence, as it no longer fit.

2.6.3

Paragraph 4: Think this needs some source material.

We have added citations to this section.

2.6.4

Paragraph 1, Word, "acceptance": Incentivization form?

Keeping in mind that "acceptance" has
been defined and therefore has specific
meaning in this report, we mean the
sentence exactly as stated.

3.3

"Another study focused on PEV adoption in California showed
that one additional BEV or PHEV within a one-mile radius of a
Census block group would increase BEV sales by 0.2 percent in
the block group (Chakraborty, Buch, and Tal 2021), reinforcing
the finding that exposure is linked to PEV awareness and
subsequent stages of acceptance.": 1 cannot find this in this
source. Neither the policy brief nor the associated report
mentions this finding. Additionally, it is generally difficult to
disentangle self-selection and correlated environmental factors
from social influence.

We have corrected this citation to
Chakraborty et al. 2022.

4.2

This section would serve well with subheadings for
infrastructure, vehicle availability, and affordability.

We now include these subheadings within
section 4.2.

4.2

We deleted this paragraph.

We deleted this paragraph.

4.4

"A long waiting period between ordering and receiving a new
PEV for recent models is another factor that makes PEVs less
appealing to some consumers, especially if the need to acquire
a new vehicle is urgent (Matthews et al. 2017b)." You may also
consider this an obstacle to adoption (a person could approve
of EVs but their decision timeframe for a particular purchase is
reduced because there actual next purchase was unplanned
(e.g. incapacitated vehicle)).

We have revised this paragraph to better
align with Dr. Maness1 point.

18


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Continuation of Table 9. Reviewer Comments by Report Section: Dr. Maness

Section

Reviewer Comment

Response

5.3

'Thus, the enablers of awareness and access previously
discussed also enable approval. These enablers include
exposure, advertising, education, affordability, incentives,
charging infrastructure, and PEV availability.": Does this not
work against the separation into 4 distinct stages. Seems
that the enabling of approval is just the previous stages
(increased awareness and better access), not the enablers
of those stages. The division of the section seems to
suggest that the enablers are: competitive advantage,
acceptable access, and normalization.

As stated in Section 1.3, the 4-A framework is
a "stylized representation" of a process,
consisting of 4 stages that is not a "strictly
ordered continuum." We also stated that "the
components are not mutually exclusive." In
Section 5.3, we intend to convey that
awareness and access directly enable
adoption. We also intend to convey that the
enablers of awareness and access indirectly
enable approval. Lastly, we intend to convey
that the enablers of awareness and access can
also directly enable approval. We've rephrased
this section to bring more clarity based on Dr.
Maness1 comment. We also would like to
acknowledge that the categories of enablers
suggested by Dr. Maness - competitive
advantage, acceptable access, and
normalization - nicely articulate elements of
the second dimension of our framework -
consumers, vehicles, and systems - illustrated
in Figure 2 and discussed in Section 2.
"Competitive advantage" speaks to the
alignment between consumer criteria and
vehicle attributes (Section 2.2). "Acceptable
access" speaks to the role of physical,
government, and market systems that make
PEV adoption easier or harder (Sections 2.6.1,
2.6.3, and 2.6.4). "Normalization" speaks to
the social systems in which consumers form
perceptions (Section2.6.2).

5.3

This seems like competitive advantage.

In accordance with Dr. Maness1 suggestion, we
added subheadings to Section 5.3. We call the
first subsection "Alignment between
Attributes and Criteria," rather than
"Competitive Advantage," which we believe
better represents the content.

5.3

This seems like acceptable access

Following Dr. Maness1 suggestion, we have
created a subsection called "Acceptable
Access."

5.3

"[...] pro-PEV policies is associated with higher levels of PEV
approval": May want to consider these sources on the
effectiveness of incentives:

Jenn A, Springel K, Gopal AR. Effectiveness of electric
vehicle incentives in the United States. Energy policy. 2018
Aug l;119:349-56.

Wang N, Tang L, Pan H. A global comparison and
assessment of incentive policy on electric vehicle
promotion. Sustainable Cities and Society. 2019 Jan
l;44:597-603.

We have added the suggested reference.

19


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Continuation of Table 9. Reviewer Comments by Report Section: Dr. Maness

Section

Reviewer Comment

Response

5.3

"Free and low-cost charging also contribute to the intent to
adopt as well as on sales (Maness and Lin 2019). The
presence of discounted, free, and/or designated PEV
parking spaces has also been found to increase the intent to
adopt a PEV, as do non-financial interventions, such as HOV
lane access." May consider this Scandanavian study that
examines both parking and charging discounting in a SP
setting:

Langbroek JH, Franklin JP, Susilo YO. The effect of policy
incentives on electric vehicle adoption. Energy Policy. 2016
Jul 1;94:94-103.

We have added this reference with a note that
it is in the context of Scandanavia.

5.3

This seems like (social) normalization

Following Dr. Maness1 suggestion, we have
created a subsection here called
"Normalization of PEVs."

5.4

"Whether and why the benefits of home charging outweigh
concerns about reliability and safety differ from one
consumer to the next, which could make a messaging
campaign, for example, effective for one group and
counterproductive for another. Regarding uncertainty,
some PEV attributes, such as range, charging practices,
maintenance, and operating costs, are unfamiliar to
prospective adopters by virtue of the dominance, maturity,
and inertia of ICEV markets and fueling infrastructure, but
ultimately knowable in the short term. Other uncertainties,
such as battery life and infrastructure availability, are
unknown in the short term and may remain so for some
time. Uncertainties, especially those related to range,
infrastructure availability, and unfamiliar practices (e.g.,
charging rather than fueling) precipitate anxiety.": Citations
would be helpful here. Risk aversion?

We have added several citations regarding
consumer behavior to this section.

6.1

Word, "percentages": Rates?

We added "rates" to this paragraph, along
with an example of a rate that measures
adoption.

6.3

"[...] and thus, enablers at every stage of the 4-A framework
can directly or indirectly enable adoption.": See my similar
statement before. 1 think the list that follows is more
specific that once it is in my consideration set, what steps
can be taken to move towards adoptions, what can make
this easier or harder.

For increased clarity, we modified our text. In
addition, note that as stated in Section 1.3, the
4-A framework is a "stylized representation"
of a process, that is not a "strictly ordered
continuum" with components that "are not
mutually exclusive."

6.3

A previous section talks about the complexity of tax
rebates. It seems like a complex tax rebate or like the time
between incentive receipt and purchase are things that
may inhibit adoption. Those complexities probably have
less effect on someone thinking an EV is worthy of
considering (you would need to really dig into the policy to
understand this which is closer to the decision stage and
less at gaining awareness/knowing that incentives are
possible).

We have added text to highlight the potential
effect of incentive design on adoption
outcomes.

20


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Continuation of Table 9. Reviewer Comments by Report Section: Dr. Maness

Section

Reviewer Comment

Response

6.3

'The process of obtaining rebates and tax credits can be
confusing for consumers, and not all consumers are
aware that such incentives are available to assist with
the expense of PEV purchases. An additional
consideration is that PEV buyers so far have tended to
be those with high incomes, so rebates and incentives
may accrue to consumers already likely to purchase
PEVs without an intervention. Some studies suggest that
caps on vehicle price and/or on buyer income can
increase the likelihood that the recipient of a purchase
incentive would not have purchased a PEV otherwise,
improving the equity of PEV incentives (Linn 2022).":
These seem more like Obstacles.

We agree with Dr. Maness. As previously written,
we appear to be describing obstacles. Our
intended message was that incentives enable
adoption, but the context, design, and
implementation of incentives may diminish the
policy's full potential due to, for example,
awareness, confusion and timing. For clarity in
this section, we eliminated text regarding
"confusion" and "awareness" among consumers.
We speak to this in Sections 3 and 4 instead. We
moved the remainder of this text to a footnote as
it speaks more to distributional outcomes than to
adoption enablers.

6.3

1 am not sure 1 see what here changes from approval to
adoption. What about HOV lanes makes someone more
likely to adopt after they've added an EV to their
consideration set? It seems like an incentive that confers
competitive advantage, which was a theme in approval.

We agree that access to HOV lanes likely
increases the likelihood that a PEV enters into an
individual's consideration set, and therefore
indirectly influences adoption through approval
as Dr. Maness points out. However, in some
studies that include HOV lane access, the
outcome measured (i.e., the dependent variable)
is an adoption metric (e.g., sales). Since our
review is written to reflect the literature as well
as interpret it, we include HOV lane access in our
discussion of adoption enablers as well. We have
added a footnote where we lay out our rational
for discussing the topic here.

6.3

"Expanding charging networks and increase charging
accessibility through interventions, such as increasing
the number of public chargers, providing free or low
cost public charging, and subsidizing the installation of
at-home chargers, are associated with higher adoption
rates (e.g., Zou, Khaloei, and Mackenzie 2020).":May
want to consider this source that shows that increased
fast charging was associated with longer daily/weekly
driving distances:

Neaimeh M, Salisbury SD, Hill GA, Blythe PT, Scoffield
DR, Francfort JE. Analysing the usage and evidencing the
importance of fast chargers for the adoption of battery
electric vehicles. Energy Policy. 2017 Sep l;108:474-86.

We added the suggested citation to this
paragraph.

21


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Continuation of Table 9. Reviewer Comments by Report Section: Dr. Maness

Section

Section

Section

6.4

1 think this makes more sense in the previous section.
Along with the test drive mention. If you visit a
dealership, it can often mean you are considering
adopting.

Dealerships have opportunities to enable PEV
acceptance throughout the vehicle purchase
process. Indeed, they may be especially well suited
to facilitate the shift from approval to adoption
since many consumers interact with dealers at the
actual time and location of purchase. Thus, we
agree with Dr. Maness that a discussion of
dealerships should appear among enablers in
Section 6.3. In addition, studies show that PEV
acceptance has not consistently been supported at
dealerships. Therefore, it is necessary to include
dealership practices among possible obstacles and
cite those studies in Section 6.4. To that end,
several revisions were made to Section 6.3 and 6.4
to incorporate these ideas.

7

Word, "compromise": Comprise.

We have corrected this typographical error.

7.3

"Although, monetary and nonmonetary metrics and
measures of approval vary widely, altogether the
literature suggests that more than half of consumers
believe PEVs are as good as ICEVs.": This does not
follow from the prior discussion that about half of
Americans are aware of PEVs (Awareness Synthesis).
How could they all then believe PEVs are at least as
good? (1 understand these are from varying studies, but
from the framework, it just does not seem logical).

In the Awareness Synthesis, we state "The percent
of U.S. vehicle consumers who are aware of PEVs
ranges from roughly the mid-teens to the low
eighties," with the higher percentages associated
with more generalized forms of awareness (e.g.,
understands PEV powered by electric
motor/batteries, PEVs have higher fuel economy
than otherwise similar ICEVs). This 80% broadly
aware of PEVs leaves plenty of room for "more
than half" approving of PEVs (e.g., PEVs "as good
as ICEVs"). In addition, this statement derives from
Singer (2017) which we cited in Section 5.2. We
add this citation to Section 7. While we chose to
make no further revisions, we fully appreciate Dr.
Maness1 critique, which highlights the challenge of
synthesizing many studies with many different
study populations and many different metrics.

7

Image has presentation mode artifacts.

We sincerely appreciate this attention to detail.

General

The method of exploring the literature could use some
additional explanation. It is good that the thoroughness
of the literature search is explicitly mentioned, but
perhaps the base papers that were used to start the
discussion could be mentioned and the search terms
used.

We have expanded the description of our search
method.

22


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