Event data recorder: what your car’s black box saves, what it misses and who can read it
When the recorder saves data, where it falls short and what to ask before a download
Safety Behind the Wheel Foundation built this guide from National Highway Traffic Safety Administration (NHTSA) guidance and federal event data recorder rules, the federal Driver Privacy Act, state laws in Virginia, Texas, Washington, New York and Oregon, and published research, including a study by the Insurance Institute for Highway Safety (IIHS). Every source is listed at the end.
What an event data recorder is
An event data recorder, or EDR, is often called a car’s black box. It is a function in the vehicle’s electronics that saves technical data for a brief time before, during and just after a collision [1]. The National Highway Traffic Safety Administration (NHTSA), the federal vehicle safety agency, describes that window as seconds, not minutes [1].
In most vehicles, the EDR is part of the air bag control module, the small computer that runs the air bags [2]. Capacitors hold backup power, so the recorder can keep working if the collision cuts off the main battery [2].
EDRs are now close to universal. NHTSA estimates that 99.5 percent of model year 2021 passenger vehicles rated at 8,500 pounds or less had an EDR that meets the federal rule [2]. That weight rating is the most the vehicle is designed to weigh fully loaded.
Why “black box” is a misleading nickname
After a serious car accident, families often hear that the car’s “black box” will show what happened. The nickname makes many people picture a hidden camera, a microphone or a log of every trip. That picture is wrong. It can raise false hopes, or needless fears about being watched.
The federal EDR rule defines the device as one that records the vehicle’s changing data during the short period just before a collision [3]. Think of it as a few frames of technical data, not a movie. Three questions matter most. What did it save? How far can it be trusted? And who may read it?
What an EDR does not record
Many fears about the “black box” come from mixing it up with other devices.
Comparison compiled by Safety Behind the Wheel Foundation
Common beliefs about a car's black box
| Common belief | What the rules say |
|---|---|
| It films the accident. | NHTSA’s use of “EDR” excludes devices that make video recordings [1]. |
| It records what people said in the car. | The term also excludes audio recorders [1]. |
| It logs every trip I take. | Nothing is recorded under normal driving conditions [15]. |
| It stores my name and where I crashed. | The required manual statement says no personal data, including crash location, is recorded [15]. |
| It holds minutes of driving. | It covers seconds, typically 30 or less in all [1, 15]. |
| Every car must have one. | The federal rule sets standards only for vehicles that have an EDR [3]. |
The same manual statement adds a caution. Police and others can combine EDR data with the personal details they routinely collect in an accident investigation [15]. The file may not carry your name, but once it is matched to a crash report, it is about you.
Other devices may record what the EDR does not
A dash cam records video. Navigation systems, connected car services and phones can store location and trip history. Those systems have their own rules. Some state laws also reach beyond the federal EDR definition. New York’s law covers recording devices that can record a vehicle’s location or send crash information to a central communications system [16]. Washington’s law covers systems that record sensor data even when recording is not their main job [14].
How an EDR decides what to keep
An EDR is always watching but rarely saving. The federal rule separates two steps. To “capture” means to hold data in temporary memory that is updated over and over. To “record” means to save it in permanent memory so it can be read later [3].
What sets it off and what happens next
The federal rule, known as 49 CFR Part 563, defines the trigger. An “event” is a crash or jolt that changes the vehicle’s speed by 8 kilometers per hour (about 5 mph) or more within 0.15 seconds [3]. An event also occurs when a one time restraint, such as an air bag, deploys [3].
What happens next depends on the type of event:
- Air bag deployment. The recorder must save the data and lock that memory so later events cannot write over it [3].
- No deployment. The automaker may save the event, write over an older event of the same kind, or not save it [3]. NHTSA notes the recorder can hold up to two of these events [2].
So a record from a minor jolt might be replaced by a later one. A record tied to an air bag deployment should stay put.
What the federal rule says it must record
Part 563 covers cars, SUVs, pickups, vans and buses built on or after September 1, 2012, that are rated at 8,500 pounds or less [3]. It does not force automakers to install an EDR. It sets the rules for any vehicle that has one [3].
Every covered EDR must capture a core set of data. The table below sums up that list in plain words [3].
Comparison compiled by Safety Behind the Wheel Foundation
Data a covered event data recorder must capture
| What it captures | What it means | When |
|---|---|---|
| Vehicle speed | Speed as the car’s own sensors read it | Seconds before the crash [3] |
| Gas pedal (throttle) | How far the pedal was pressed, in percent | Seconds before the crash [3] |
| Service brake | Whether the brake pedal was pressed: on or off | Seconds before the crash [3] |
| Driver seat belt | Buckled or not | 1 second before [3] |
| Air bag warning light | Whether the warning light was on | 1 second before [3] |
| Front air bag timing | How long each front air bag took to deploy | During the crash [3] |
| Delta V | How much the vehicle’s speed changed in the impact | Up to the first quarter second of the crash, at 100 readings per second [3] |
| Ignition cycles | How many times the car had been started | At the crash and at download [3] |
| Event count and file status | How many events, and whether each record is complete | After the crash [3] |
Delta V is the change in a vehicle’s speed and direction during the impact. Researchers use it as the main measure of crash severity, a key predictor of injury in frontal collisions [4].
If a vehicle has certain other features, the EDR must record them too. Examples include steering, antilock brake activity, stability control, the front passenger’s belt, side air bags and seat belt pretensioners [3]. A pretensioner pulls the belt tight at the start of a crash.
The window before a collision is getting longer
Today, a covered EDR must save at least 5 seconds of speed, gas pedal and brake data before a collision, at two readings per second [5]. In December 2024, NHTSA issued a final rule to stretch that to 20 seconds at 10 readings per second, as Congress directed [2]. The agency said a longer record could fully capture a driver rolling through a stop sign or a red light [2].
In May 2026, after automakers asked for more time, NHTSA dropped the original 2027 start date and set a phase in [6]. A quarter of each automaker’s covered vehicles built from September 1, 2028, must comply, rising to all vehicles built on or after September 1, 2031 [6]. Small volume automakers and companies that finish or alter vehicles get until 2032 and 2033 [5].
How an analyst reads the record
An EDR report looks precise, but it is one strong piece of evidence, not the whole story.
A careful review typically follows this order:
- Confirm the legal right to read the data, such as the owner’s written consent or a court order.
- Match the module to the vehicle, using the vehicle identification number (VIN) and photos.
- Retrieve the data with the tool built for that vehicle, and keep the original file unchanged.
- Check the event list: how many events were saved, which are locked, and whether each file is complete.
- Compare the two ignition cycle counts. The gap shows how many times the vehicle was started between the collision and the download.
- Build a timeline of speed, brake and gas pedal before impact, then delta V during it.
- Test that timeline against the scene, the damage, any video and witness accounts.
- Write down what the data cannot show.
Two limits come up again and again:
Speed readings, timing gaps and other limits
A careful analyst treats the record as one witness among several. Four more limits show why.
Speed is what the car thought it was going
In a 2023 forensic study of one 2019 European compact car, investigators traced the recorded speed to the average of the two front wheel speeds. That reading was about 5 percent off from the true speed [7]. One car is not every car, but it shows why analysts learn how each model measures speed. An analyst also asks whether wheels were locked or spinning, which can throw off a speed taken from wheel sensors.
There are gaps between readings
At 2 readings per second, half a second passes between samples [5]. Researchers have had to allow for this uncertainty in exactly when braking and steering began [17]. NHTSA said faster sampling under the new rule will reduce it [2].
Records can be cut short or written over
The rule requires a yes or no flag that shows whether the file was recorded completely [5]. Data from a collision without a frontal air bag deployment may also be overwritten [3]. In standard crash tests, the data must stay readable for at least 10 days [3]. That is a lab standard, not a promise about every real crash.
Some questions it cannot answer
An EDR does not record who was driving, what the driver saw, whether a phone was in use or what the other car did. Those answers come from the scene, photos, video, witnesses and the police report.
Why a short technical record still matters
A few seconds of data can still answer key questions. Was the car speeding up or slowing down? Was the brake pressed? Was the belt buckled? Memory after a wreck is often patchy, and this data does not depend on anyone’s recall.
Researchers have used EDRs to see what drivers do in the last second before impact. In a study of intersection collisions, drivers tried to avoid the collision in about four out of five cases [17]. The typical driver began braking between half a second and 1.5 seconds before impact [17]. For a family, data like this can show that a loved one reacted, even when nobody remembers it.
How investigators and researchers use the data
EDR data fills gaps that physical evidence cannot. Crash technicians in NHTSA’s national investigation sample already document skid marks, fluid spills, struck objects and vehicle damage [8]. NHTSA says it has used EDR data in its crash investigations for years and routinely adds it to its crash databases [1].
One study looked at 228 frontal collisions where investigators had reconstructed delta V and an EDR had also measured it [4]. The reconstructed values averaged 19 percent lower than the EDR readings [4]. Estimates that run low can make collisions look milder than they were and skew studies of injury risk [4].
EDR data also answers questions about everyday driving. An Insurance Institute for Highway Safety (IIHS) researcher used EDR speed data from 436 rear end collisions in a federal sample from 2017 to 2020 [9]. On roads posted at 25 mph or less, striking vehicles were often going much faster than the limit [9]. The study used those results to suggest how tests of automatic emergency braking could better match real collisions [9].
NHTSA notes that insurers, researchers, automakers and regulators can use EDR data to understand what causes collisions and how safety gear performed [2]. Researchers have also studied using EDR measures to predict injuries right after a collision, so emergency crews can plan care [10]. EDR data may also be offered as evidence in court, and how it is treated there is a question for a lawyer.
All of this serves the rule’s purpose. Part 563 aims to capture data that helps crash investigations and shows how safety equipment performed, so future designs can protect people better [3]. Safety Behind the Wheel Foundation supports that goal.
Who owns the data and who can read it
Federal law settles ownership. The Driver Privacy Act of 2015, which became law on December 4, 2015, says EDR data belongs to the vehicle’s owner, or to the lessee if the vehicle is leased [11]. That is true no matter when the vehicle was built [11].
The same law says no one but the owner or lessee may access the data unless one of these applies [11]:
- A court, or another judicial or administrative body, authorizes it.
- The owner or lessee agrees in writing, electronically or by recorded audio, for any purpose, including repair.
- It is retrieved in a federal safety investigation or inspection by NHTSA or the National Transportation Safety Board, without revealing personal information or the VIN. The VIN may go to the maker.
- It is needed for emergency medical response after a crash.
- It is used for traffic safety research, without revealing personal information or the VIN.
The federal list has no separate line for police or insurance companies. Outside the listed cases, access depends on consent or an order [2, 11].
Reading the data takes a special tool and physical access to the car or its module [3]. Each automaker must make sure a retrieval tool is sold commercially within 90 days after the vehicle’s first retail sale [3]. That makes a download a job for someone trained on the tool, such as a crash data technician or reconstructionist.
Borrowed cars and other systems in the car
State laws add their own rules
Several states have their own EDR laws on disclosure, consent and access. Three examples show how they differ.
Comparison compiled by Safety Behind the Wheel Foundation
Who may read EDR data without consent in three states
| State | Who may access without the owner’s consent | A notable rule |
|---|---|---|
| Virginia | Courts; police where the Constitution allows; repair technicians; emergency responders; subscription services | Insurers may not seek consent before the accident or make it a condition of paying a claim [12] |
| Texas | Courts; safety researchers who keep identity private; emergency medical response | The owner’s manual must disclose the device [13] |
| Washington | Courts; safety researchers who keep identity private; emergency medical response; disclosed subscription services | Consent covers one specific access. Violations are a misdemeanor [14] |
In Virginia, police access must follow search and seizure law based on probable cause [12]. The insurer rule protects families at a hard moment. Consent to use the data for a claim cannot be a condition of defending, paying or settling it [12].
Texas also says a subscription service contract must tell customers about the device’s recording [13]. Washington treats a violation as a misdemeanor and as a breach of its consumer protection law [14].
Other states have different rules, and some have none. Look up your own state’s law before you rely on any of these points.
More state rules, including New York and Oregon
New York and Oregon have their own EDR laws too. This table adds them, with a shorter summary of Virginia and Washington, as of October 2026.
Comparison compiled by Safety Behind the Wheel Foundation
Key EDR rules in four states
| State | Key rules |
|---|---|
| Virginia | Access needs the owner’s consent or a listed exception, such as a court order. Consent for a crash or claim investigation cannot be sought before the accident [12]. |
| Washington | Others need consent for each access, a court order or discovery, or a research, emergency or subscription purpose. Violations are misdemeanors [14]. |
| New York | Recorders must be disclosed with the owner’s manual. Only the current owner may retrieve data, apart from consent, court orders, research, repairs or emergency care [16]. |
| Oregon | Sections cover data ownership, court orders for police or insurer retrieval, and limits on insurer and lessor actions [18]. |
Virginia’s law also says the owner’s rights to the device and its data survive a sale to an insurer or salvage yard [12]. That can matter when a car is declared a total loss. Washington requires owner’s manuals to say what data is recorded and whether the device can send information to a central system [14].
Before you agree to a download
After a serious collision, someone may ask you to sign a form allowing a download of your vehicle’s data. You may also want the data yourself. Either way, slow down and ask questions first.
Keep the vehicle and its air bag module together until you decide. Once a vehicle is repaired, scrapped or sold, the module may be gone. A companion article covers preserving a badly damaged vehicle.
If a download happens, ask for the full report in its original file format and a printed copy. Note the date, who did the download, and where the vehicle was. Keep these with your other crash records.
More practical steps after a serious collision
You do not need to be a data expert to take these steps.
- Find out what your vehicle has. Look in the owner’s manual for the required EDR statement [15], and note any dash cam or connected services.
- Get help reading the data. An independent crash reconstruction professional can compare it with the scene, and a lawyer can explain your rights.
Frequently asked questions
Does my car have an event data recorder?
Most likely. NHTSA estimates that 99.5 percent of model year 2021 passenger vehicles rated at 8,500 pounds or less had one that meets the federal rule [2]. Look for an event data recorder section in your owner’s manual. Any vehicle with a covered EDR must include that notice [3]. Vehicles built before September 1, 2012, fall outside the federal rule, so what they save can vary [3].
Does the EDR record my location, voice or video?
The federal list does not include location, and the required owner’s manual notice says crash location is not recorded [3]. NHTSA’s definition of an EDR also excludes devices that record sound or video [1]. Other systems in your car, such as connected services or a dashcam, are separate and follow different rules.
Will the EDR prove who caused the accident?
Not by itself. An EDR can show what one vehicle was doing in the seconds before impact, such as its indicated speed and whether the brake was on [5]. It cannot show who was driving or what the other driver did. Recorded speed can also differ from true speed [7]. A reconstruction professional combines the data with scene evidence, photos and witness accounts.
Can the police download my car’s EDR?
Federal law lists court authorization and owner consent among the ways someone other than the owner may retrieve the data [11]. The required owner’s manual statement notes that police can read the data if they have the equipment and access to the vehicle [15]. Washington and New York also allow access with a court order [16, 14]. A lawyer can explain how the rules apply to you.
Can my insurance company get my EDR data?
Under federal law, the data belong to you, so an insurer generally needs your consent or a court order [11]. Some states add protections. Virginia bars insurers from asking for consent before the accident or making it a condition of paying a claim [12]. Read any form and your policy before you sign. Your state insurance department can explain the rules where you live.
Can I get a copy of my own EDR data?
Yes. Under federal law, the owner or lessee owns the data [11]. Reading it takes a special tool and physical access to the car or its module [3]. A trained crash data technician or crash reconstructionist can do the download. Ask for the full report and the original file, and ask them to explain any limits in the data.
The bottom line
Recommendation from Safety Behind the Wheel Foundation
Safety Behind the Wheel Foundation urges families to slow down, ask questions and read every form before anyone downloads their car’s data. Your car’s event data recorder holds a short, technical snapshot of a collision: speed, pedals, seat belt and air bag timing. It does not record your whole drive, your voice or where you go. That snapshot can help investigators and families understand what happened, but it works best alongside the scene, the damage and other records.
You own that data under federal law, and your state may add more protection. Before you agree to a download, ask who wants it, why, and what you will receive. If someone was badly hurt or fault is disputed, talk with a lawyer first.
Related articles
Sources and further reading
- 1National Highway Traffic Safety Administration. Event Data Recorder. No update date shown; accessed October 2026. nhtsa.gov/research-data/event-data-recorder
- 2National Highway Traffic Safety Administration, Federal Register. Event Data Recorders (final rule), 89 FR 102832. Published December 18, 2024. Data year: model year 2021 (equipment estimate). govinfo.gov/link/fr/89/102832
- 3U.S. Government Publishing Office and Office of the Federal Register, Electronic Code of Federal Regulations. 49 CFR Part 563, Event Data Recorders. Up to date as of October 1, 2026. ecfr.gov/…/part-563
- 4Funk JR, Cormier JM, Gabler HC. Effect of delta-V errors in NASS on frontal crash risk calculations. Annals of Advances in Automotive Medicine, vol. 52, pp. 155-164 (via PubMed). Published 2008. Data year: NASS 1997-2006. pubmed.ncbi.nlm.nih.gov/19026232
- 5U.S. Government Publishing Office and Office of the Federal Register, Electronic Code of Federal Regulations. 49 CFR 563.7, Data elements. As amended May 18, 2026 (91 FR 28440). ecfr.gov/…/section-563.7
- 6National Highway Traffic Safety Administration, Federal Register. Event Data Recorders (final rule; response to petitions for reconsideration), 91 FR 28440. Published May 18, 2026. govinfo.gov/link/fr/91/28440
- 7Spek A, Otjens J. Understanding pre-crash speed sampling by the VAG Event Data Recorder. Forensic Science International, vol. 351, 111831 (via PubMed). Published 2023. pubmed.ncbi.nlm.nih.gov/37722312
- 8National Highway Traffic Safety Administration. Crash Investigation Sampling System. No update date shown; accessed October 2026. nhtsa.gov/…/crash-investigation-sampling-system
- 9Kidd DG, Insurance Institute for Highway Safety. Can the speed limit be used as a surrogate for the striking vehicle’s travel speed or delta-V in police-reported rear-end crashes? Traffic Injury Prevention, vol. 24, no. 3, pp. 178-183 (via PubMed). Published online 2022. Data year: 2017 to 2020. pubmed.ncbi.nlm.nih.gov/35929865
- 10Weaver AA, Talton JW, Barnard RT, Schoell SL, Swett KR, Stitzel JD. Estimated injury risk for specific injuries and body regions in frontal motor vehicle crashes. Traffic Injury Prevention, vol. 16, suppl. 1, pp. S108-S116 (via PubMed). Published 2015. Data year: NASS-CDS (years as reported in the study). pubmed.ncbi.nlm.nih.gov/26027962
- 11U.S. Government Publishing Office, United States Code. 49 U.S.C. 30101 note: Driver Privacy Act of 2015 (Pub. L. 114-94, div. B, title XXIV, subtitle C). 2023 edition; enacted December 4, 2015. govinfo.gov/…/USCODE-2023-title49-subtitleVI-partA-c…
- 12Virginia General Assembly, Code of Virginia. Section 46.2-1088.6, Motor vehicle recording devices. Accessed October 2026. law.lis.virginia.gov/…/section46.2-1088.6
- 13Texas Legislature. Transportation Code, Chapter 547, Section 547.615, Recording Devices. Accessed October 2026. statutes.capitol.texas.gov/…/TN.547.htm
- 14Washington State Legislature. Chapter 46.35 RCW, Recording devices in motor vehicles. Accessed October 2026. app.leg.wa.gov/…/default.aspx?cite=46.35&full=true
- 15Electronic Code of Federal Regulations (eCFR). 49 CFR 563.11 – Information in owner’s manual. Up to date as of October 1, 2026. ecfr.gov/…/section-563.11
- 16New York State Senate. New York Vehicle and Traffic Law § 416-B: Vehicle data recording devices. Revision dated September 22, 2014, accessed October 2026. nysenate.gov/legislation/laws/VAT/416-B
- 17Traffic Injury Prevention (Scanlon, Kusano and Gabler), via PubMed. Analysis of Driver Evasive Maneuvering Prior to Intersection Crashes Using Event Data Recorders. Published 2015. Data year: NASS-CDS 2001-2013. pubmed.ncbi.nlm.nih.gov/26436230
- 18Oregon State Legislature. Oregon Revised Statutes Chapter 105 (ORS 105.925 to 105.945, motor vehicle event data recorders). Accessed October 2026. oregonlegislature.gov/bills_laws/ors/ors105.html
This article reflects the safety priorities of vehicle data privacy and fair treatment of families after a serious collision. It is general education, not legal, insurance or professional advice. Federal and state rules change, so verify details with official sources. For your own situation, contact your state insurance department or DMV, check your state legislature's website, or speak with a qualified independent crash reconstruction professional or a lawyer licensed in your state. Reviewed October 2026.
Cite this article: Safety Behind the Wheel Foundation. “Event data recorder: what your car’s black box saves, what it misses and who can read it.” drivewithcare.org, https://drivewithcare.org/what-your-event-data-recorder-can-reveal/. Reviewed October 2026.
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