Improving Equitable Electric Vehicle Adoption Study (IEEVAS)

Last registered on June 29, 2026

Pre-Trial

Trial Information

General Information

Title
Improving Equitable Electric Vehicle Adoption Study (IEEVAS)
RCT ID
AEARCTR-0018940
Initial registration date
June 23, 2026

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
June 29, 2026, 8:36 AM EDT

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Locations

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Primary Investigator

Affiliation
UCSD

Other Primary Investigator(s)

PI Affiliation
UCSD
PI Affiliation
UC Davis
PI Affiliation
UC Davis
PI Affiliation
Yale

Additional Trial Information

Status
In development
Start date
2026-05-27
End date
2028-07-15
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
Subsidies for pro-social behaviors—such as adopting electric vehicles (EVs), heat pumps, or other decarbonization technologies—are frequently criticized for being non-additional and regressive. Higher-income households tend to claim subsidies they would have used anyway, while lower-income households often remain constrained by financial, informational, and behavioral barriers. To design more equitable and cost-effective programs, policymakers require evidence not only on how many low- and moderate-income (LMI) households would adopt these technologies at different subsidy levels, but also on how the structure and salience of subsidy offers affect purchase intent, uptake, and the distribution of benefits. We partner with an electric utility and car dealerships to implement a large-scale, two-stage randomized controlled trial across approximately 100,000 LMI households to address these gaps. Combining surveys, negotiated vehicle prices, and vehicle registration records, the study will provide policymakers with experimentally estimated demand curves for EV subsidies among LMI households, evidence on behavioral responses to alternative incentive structures, and the first experimental measures of dealer pass-through in EV subsidy programs.
External Link(s)

Registration Citation

Citation
Garg, Teevrat et al. 2026. "Improving Equitable Electric Vehicle Adoption Study (IEEVAS)." AEA RCT Registry. June 29. https://doi.org/10.1257/rct.18940-1.0
Sponsors & Partners

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Experimental Details

Interventions

Intervention(s)
Intervention Start Date
2026-07-15
Intervention End Date
2027-07-15

Primary Outcomes

Primary Outcomes (end points)
Application Take-Up ( whether a household initiates and completes an application), Willingness-to-Accept (BDM) an alternative rebate, Vehicle puchase/lease, Subsidy Pass-Through
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
This study evaluates how program design affects participation in and take-up of electric vehicle incentives among low- and moderate-income households. The trial has three main stages, each involving a distinct randomized comparison between treatment and control groups.

In the first stage, households are randomly assigned to receive different outreach messages describing alternative incentive amounts and allocation rules (treatment groups), while some households will not receive them (control group). This randomization allows us to estimate how program framing affects application behavior, applicant selection, and demand for the program. Applicants who choose to apply complete an intake form that includes demographic, transportation, and charging-access questions, as well as an incentive-compatible preference-elicitation exercise for an alternative rebate.

In the second stage, eligible applicants are randomly assigned either to receive an additional subsidy top-up (treatment group) or to receive only the baseline incentive for which they qualify (control group). Using application records, dealership data, and administrative data, we will estimate the effect of the top-up on vehicle purchase and leasing decisions, including whether households acquire a vehicle and the type of vehicle acquired.

In the third stage, among households receiving incentives, applicants are randomly assigned to disclose subsidy information during the vehicle transaction process, while in the control group information will not disclosed. Comparing negotiated vehicle prices across these groups will allow us to estimate subsidy pass-through and the extent to which incentives are captured by consumers versus dealerships.

Together, these stages provide evidence on participation in subsidy programs, the responsiveness of vehicle purchases to financial incentives, and the incidence of EV subsidies.
Experimental Design Details
Not available
Randomization Method
Randomization done in office by a computer.
Randomization Unit
The unit of randomization is the household, since they will be invited to participate and we will allow one program application per household.
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
Around 100,000 households will be invited to apply, but only 200 households will receving the rebate and top-ups.
Sample size: planned number of observations
Around 100,000 households will be invited to apply, but only 200 households will receving the rebate and top-ups.
Sample size (or number of clusters) by treatment arms
In Stage 1 we expect a 33/33/33% split between two main treatment arms and control. In Stage 2, 2/3 of the incentive winners will get a top-up. In Stage 3, 50% of top-up receivers will also get a treatment information.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB

Institutional Review Boards (IRBs)

IRB Name
UC San Diego Institutional Review Board Administration
IRB Approval Date
2026-05-27
IRB Approval Number
814205