The US National Highway Traffic Safety Administration has widened a safety investigation into General Motors after hundreds of reports of brake failure linked to the automaker's "eBoost" brake-by-wire system. The fault, which involves a spindle fracture that can occur while a vehicle is being driven, affects more than 1.1 million vehicles, including several GM electric models as well as vehicles it manufactures for Honda and Acura. The escalation matters because it raises questions about whether GM's own safety assurances about the fault match what drivers are actually experiencing on the road.

GM has said that even if a spindle fracture occurs, key safety systems such as antilock brakes, traction control and stability control should remain functional until the vehicle comes to a complete stop. However, regulators say many reports contradict this, describing an immediate loss of braking following an eBoost failure. NHTSA has logged 227 incident reports directly, rising to 745 when GM's own reports are included, with 22 crashes and six injuries recorded across five incidents, though no fatalities so far. Affected models span 2023–2026 model years and include the Cadillac Lyriq, Chevrolet Colorado, GMC Canyon, Buick Enclave and Envision, Chevrolet Blazer EV, Equinox EV and Traverse, Cruise Origin, GMC Acadia, Cadillac Celestiq and Optiq, plus the Acura ZDX and Honda Prologue.