Randomized Online Interventions on New Car Buying

Last registered on October 23, 2025
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Pre-Trial

Trial Information

General Information

Title
Randomized Online Interventions on New Car Buying
RCT ID
AEARCTR-0017026
Initial registration date
October 16, 2025

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
October 23, 2025, 6:41 AM EDT

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

Locations

Country
United States of America
Region

Primary Investigator

Name
mason parris-bacon
Affiliation
Dartmouth College
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Other Primary Investigator(s)

PI Name
Bruce Sacerdote
PI Affiliation
Dartmouth College
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PI Name
Johnathan Zinman
PI Affiliation
Dartmouth College
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PI Name
Apoorv Gupta
PI Affiliation
Dartmouth College
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PI Name
Morteza Momeni
PI Affiliation
Tennessee Tech University
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Additional Trial Information

Status
In development
Start date
2025-10-09
End date
2025-11-30
Keywords
Finance & Microfinance
Additional Keywords
Consumer Protection, Behavioral Interventions, Financial Literacy, Car Financing, Market Power, Junk Fees, Negotiation Strategy
JEL code(s)
D12, G22, L81. C93
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
Car purchase and financing is one of the larger financial decisions that household make.  Yet due to a combination of dealer tactics and market power, many consumers overpay for the vehicle and associated financing.   This overpayment comes from a variety of sources including junk fees, unnecessary finance and processing charges, above market interest rates, financial insurance products of limited value and car accessories and addons of limited value. Car buying is among the least pleasant experiences in the United States and we aim to make the experience less bad.  We are conducting a randomized control trial in which we will give consumers simple guidance and procedures for getting the best deal possible in the transaction. Our interventions consist of emailed materials and "pro-tips" that are desgined in partnership with Consumer Reports aimed at giving consumers an optimal strategy for purchasing a car. This study will measure the finacial benefit of this intervention, against our control of car shoppers who recive no additional tips or guidance.
External Link(s)

Registration Citation

Citation
Gupta, Apoorv et al. 2025. "Randomized Online Interventions on New Car Buying ." AEA RCT Registry. October 23. https://doi.org/10.1257/rct.17026-1.0
Sponsors & Partners
Experimental Details

Interventions

Intervention(s)
Intervention (Hidden)
Intervention Start Date
2025-10-09
Intervention End Date
2025-11-30

Primary Outcomes

Primary Outcomes (end points)
Our key outcomes include: does the subject purchase a car? What are total fees paid for the car and total fees paid for financing? What is the cost of the car relative to average purchase price for that vehicle? What add on items are purchased with the car? What is the interest rate of any financing taken? What are the fees associated with the financing? Does the consumer purchase and GAP (Guaranteed Asset Protection) Insurance? How much is spent annually on GAP insurance? Are other financial products purchased with the loan? Is the loan from the dealer or a bank?
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Using targeted google ads we recruit individuals who are actively shopping for a new vehicle. new car buyers. Once prospective buyers have provided consent and been enrolled in the study they will be randomly assigned to either the treatment or control group. Upon enrollment, the control group receives a neutral welcome message and a link with steps to provide us with information on their car purchase. The control group also receives neutral weekly follow-up emails serving as study reminders to report their car purchase status and details. These reminders are formatted identically to the treatment groups but remain neutral and provide no additional tips on how to get a good deal on their purchase and financing. Upon enrollment, those assigned treatment are sent to a new webpage with a set of "pro-tips", a "smart car buyers checklist", and are prompted to engage at the bottom of the webpage by describing how useful they found the tips. The control group also receives a weekly reminder to provide us with information on their new car purchase with the addition of reminders about the treatment content that they were initially given.
Experimental Design Details
Randomization Method
Participants are randomly asigned by our webpage.
Randomization Unit
Individual buyer
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
2000 Car Buyers
Sample size: planned number of observations
2000 Car Buyers
Sample size (or number of clusters) by treatment arms
1000 control buyers, 1000 treated buyers
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
Committee for the Protection of Human Subjects Dartmouth College
IRB Approval Date
2025-08-14
IRB Approval Number
STUDY00033446
Analysis Plan

Post-Trial

Post Trial Information

Study Withdrawal

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Intervention

Is the intervention completed?
No
Data Collection Complete
Data Publication

Data Publication

Is public data available?
No

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials