2025 GMC Acadia

I was driving my 2025 GMC Acadia Denali on [XXX] with cruise on. Suddenly sound and banner notifications were telling me that I had no brakes. I immediately hit brake to break cruise and vehicle went faster. I managed to get cruise off from steering wheel. Put flashers on and took foot completely off gas. I was very fortunate that I didn’t hit someone or that no one hit me. After about 2 miles, I was able to pull in an empty church parking lot and get stopped. After getting stopped I was 2.4 miles from [XXX]. I was towed to GMC dealership in Montgomery, AL and diagnosed with defective master cylinder and no brakes. Very concerned because GMC has not issued a recall because the master cylinder failure has occurred many times before. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Since delivery, my 2025 GMC Acadia AT4 has had severe wind noise from the driver's side window at highway speeds. The noise sounds like fingernails on a chalkboard and at times as though the window may shatter. I have taken it to the dealership 4 times with no resolution. I provided video clearly capturing the noise and was still told they could not hear it. I have confirmed the dealer road tests the vehicle in morning traffic at low speeds — where the noise cannot occur. It only happens at highway speeds. Their "cannot duplicate" finding is the result of inadequate testing, not the absence of a defect. After sitting for approximately 7 days, condensation builds up inside the cabin, indicating the driver's side window seal is improperly installed. I reported this to the dealer as well with no fix. After 4 visits, dismissed video evidence, and improper test procedures, the defect remains unrepaired. I request NHTSA investigate this as a potential widespread issue on 2025 GMC Acadia vehicles.

Our onstar module has stopped working since last November after a software update and now issues are starting to cascade causing many other electrical issues to the point that I expect the car to leave my wife and 15 month old daughter stranded. Ours and many other vehicles are having this issue and when any question is asked to gm no response is given or we’re just told to keep waiting.

The contact owns a 2025 GMC Acadia. The contact stated that while driving uphill at an undisclosed speed, the vehicle hesitated, jerked, and stalled. The vehicle was taken to the dealer, where a computer reprogramming was performed; however, the failure persisted. Additionally, the contact stated that while driving 65 MPH and merging into the left lane, the automatic emergency braking system erroneously engaged and the vehicle hard-braked, nearly causing a rear-end crash. The contact immediately depressed the accelerator pedal, and the vehicle accelerated as intended. The contact stated that the failure was intermittent and had occurred approximately six times. The vehicle was taken to the dealer, where the cause of the failure could not be determined; however, the dealer advised the contact that the failure might be related to the camera system. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline for assistance. The failure mileage was approximately 3,000.

Today, June 11, 2026, my wife and 9 month old baby were on their way home from running errands in town when the vehicle started to violently shake, becoming frightened my wife tried to apply pressure to the brakes. When she pushed down on the brake pedal nothing happened and the pedal hit the floor. Our brand new 2025 GMC Acadia AT4 had just suffered catastrophic brake failure. So she pulled off onto the side of the road in hopes the uneven terrain would slow her down just enough to put it into park. Luckily enough it did. If it would have been 10 seconds later she would have been on a one way bridge where the speed limit is 60mph with no brakes. Four days prior to today on June 07, 2026 I sent a message to the individual that I bought the car from at the GMC dealership and told him that we had warning lights come up on the dash. He had me try and reset the screen but nothing happened. I asked when we could get it into a shop so it could be looked at he said that he would have someone reach out and schedule a time. I proceeded to ask if we were ok to drive the vehicle until then.To which he responded "If the vehicle isn't giving you issues mechanically, you should be good". Fast forward to today June 11, 2026 my wife is driving and has catastrophic brake failure. The vehicle was then towed by roadside assistance to the GMC dealership.

Telematic Modular Control is not working properly and part is on backorder. Dealership and GMC have refused to put into writing that my vehicle is safe to drive; however, they are refusing rental vehicle while awaiting arrival of part. Several of my safety features are not working correctly, my left turn signal went out randomly and my auto breaking has activated when there has been nothing near my vehicle.

When backing out of a parking spot of a store , I went to stop and pressing on the brakes nothing happened and I kept rolling backwards. I looked down to confirm I was pressing the brakes and my foot was on the brake pedal pressed firmly. I rolled to a stop put it in drive and checked the brakes and they worked like normal. I made an appointment at the dealership and had an appointment the next day. The said it did not have any codes, it preformed normal and passed inspected so there was nothing they could do about it.