The National Highway Traffic Safety Administration (NHTSA) published a notice in the Federal Register on June 18, 2026 setting out the reasons it denied a petition that asked the agency to open a formal defect investigation into alleged sudden unintended acceleration in a large group of Kia and Hyundai vehicles. The petition, docketed as DP21-003, was submitted on October 10, 2021 by Tom Murray of Huron, Ohio and Byron Bloch of Potomac, Maryland, and amended on August 5, 2022. According to the notice, the original and amended petitions identified 52 Hyundai and Kia models and model years, which NHTSA states encompasses approximately 6 million vehicles.

The petitioners alleged a cluster of vehicle speed control problems centered on the Electronic Throttle Control (ETC) system, which the notice records as their stated primary suspect. NHTSA's summary lists the alleged conditions as including sudden uncommanded acceleration, runaway throttle conditions, surging, stalling, and loss of motive power, and reports that the petitioners further alleged certain model year 2005-2016 Hyundai and Kia vehicles do not fully comply with Federal Motor Vehicle Safety Standard (FMVSS) No. 124, Accelerator Control Systems. The agency notes the petitioners framed the request broadly, writing in the notice's account of the filing that the petition covers events where the driver does not command acceleration or deceleration but the vehicle and ETC system act in a manner not commanded by the driver.

"After examination of the amended petition and available data relating to vehicle speed control performance of the subject vehicles, and review of FMVSS No. 124, NHTSA concluded that an investigation is not warranted. The Agency accordingly denied the petition."— Federal Register, NHTSA Notice 2026-12274, source

The notice describes the data the agency's Office of Defects Investigation (ODI) reviewed. The petitioners submitted three addenda drawn largely from NHTSA's own Vehicle Owner Questionnaire (VOQ) system: Addendum 1 alleged 566 unique VOQs related to sudden unintended acceleration (SUA), Addendum 2 alleged 601 VOQs related to loss of motive power (LOMP), and Addendum 3 listed seven VOQ cases and five non-VOQ cases of alleged SUA crashes. ODI states it performed trend analyses of the VOQs across all 52 model/model-year combinations and found that none demonstrated actionable trends that warrant an investigation.

What the event data recorders showed

The numbers ODI reports from its review form the core of the denial. For the SUA allegations in Addendum 1, the agency states it identified 512 relevant VOQs (two with duplicated ODI numbers, leaving 510 unique records) rather than the 566 alleged. Of those 510 records, 202 involved crashes, and 61 of the crash-involved vehicles were inspected by Hyundai/Kia dealer technicians, manufacturer engineers, or third-party representatives. ODI states those inspections identified no vehicle defects related to the ETC system. Among the 202 crash-involved VOQs, 50 vehicles were model year 2013 or newer and equipped with Event Data Recorders (EDRs). Ten EDR records were downloaded successfully, and the agency reports that nine of those indicated driver error, specifically pedal misapplication in which the driver depressed the accelerator instead of the brake. The remaining EDR report showed a nearly constant speed for the final five seconds before the crash, with the throttle open at 12 percent until half a second before impact and the brake not applied until just before the crash; the agency states Hyundai inspected that vehicle and could not duplicate the alleged stuck-throttle condition.

The loss-of-motive-power allegations produced a similar account. For Addendum 2, ODI found 597 unique VOQs after removing four duplicates, of which seven involved crashes; four of those vehicles were inspected, and the inspections again identified no ETC-related defects. The agency also notes it had previously examined loss-of-motive-power and non-crash engine fires on certain subject vehicles under earlier investigations numbered RQ17-003, RQ17-004, PE19-003, and PE19-004, and that those investigations identified no defect trend in the ETC system as the cause.

The contested test evidence

The petitioners supported their claims with a scientific journal paper, identified in the notice as Sungji Park et al., published in Forensic Science International in 2016, along with an oral presentation attributed to the Republic of Korea National Forensic Service. ODI describes reviewing the test setup behind the paper, in which the vehicle's 12-volt battery was replaced by a programmable test battery supplying a fluctuating voltage pattern ranging from 7 volts to 14 volts in an 8.8-second cycle. The agency states this power-supply modification does not represent a real-world condition. Reviewing five test video files, ODI reports that in two road-test videos wide-open throttle was achieved using the modified power supply and elevated accelerator-pedal positions, but that releasing the accelerator reduced the throttle and applying the brake reduced vehicle speed rapidly. On that basis the agency states it does not believe there is evidence of uncontrollable SUA in the tests reviewed.

On the alleged noncompliance with FMVSS No. 124, the notice records that NHTSA's Office of Vehicle Safety Compliance reviewed the claim and found the petitioners provided only conclusory information tied to the SUA assertion, concluding there was insufficient information to warrant investigating a potential noncompliance. The petition was signed by Eileen Sullivan, Associate Administrator for Enforcement, under authority delegated for defect petitions under 49 U.S.C. 30162(d) and 49 CFR part 552.

A procedural note in the document bears on the timeline. A footnote states that NHTSA denied the petition on June 20, 2023 and announced the denial in a closing resume, but that publication of the Federal Register notice further detailing the reasons was inadvertently delayed until this 2026 filing. The notice also states that the denial does not foreclose the agency from taking further action if warranted, or the potential for a future finding that a safety-related defect or noncompliance exists based on additional information the agency may receive. The full text and supporting figures are available under Docket No. NHTSA-2026-1387.