2026 GMC Terrain Complaint Log

I bought this car new from Davidson's in Rome, NY in early March 2026. This is a 2026 model. Two days after I took possession, I noticed that the spare tire well was halfway full of solid ice. The car has a severe leak through the back right side window. The dealer states it needs to be replaced. The interior frames of the car were loaded with water for many weeks as it stood on the lot. Had the dealer done a final inspection of this car prior to transferring ownership to me, as they should have and stated they did, they would have found the solid ice that surrounded the spare tire and investigated the leak and repaired it BUT they would have been required to tell me of this leak I assume...if so, I would never have bought this car. They had the car in the shop now for 3 weeks as of today, April 20th, 2026, and no word on the resolution. They did give me a loaner car for use. They have to dry the car out completely and dehumidify it as well as replace the window that leaked. The risks going forward is to the internal wiring, mechanicals, etc. due to static water exposure for many weeks prior to the sale. Had the dealer done their job with prior inspection, this could have been avoided. I asked them for my money back and they refused so I am stuck with a brand-new car that was essentially flooded with rainwater because the dealer did not do a final inspection prior to my accepting ownership of it. I wrote letter to all the dealership principals involved and NONE of them answered me directly...as if I was invisible or completely silent on this issue. If given an option, I would give them this car back and get a full refund.

The windshield has an optical distortion, characterized by "waviness" and "rippling." This condition is not merely a cosmetic imperfection; it is a safety hazard that causes visual impairment, and dizziness while driving. This defect compromises my ability to perceive distances and hazards accurately, especially when looking through the passenger side while making turns or looking for hazards. Current Status of the Issue as reported online Documented reports indicate that GMC dealers are aware of these "warped windshields" and that the issue appears to be a systemic quality control failure in the 2026 model year. • Safety Risk: This distortion constitutes a safety-related defect as defined by the National Highway Traffic Safety Administration (NHTSA), as it interferes with the driver's primary field of vision. •Failure of Prior Remedies: I am aware that many owners have undergone multiple replacements only to have the same defect reoccur, suggesting that current replacement stock may also be compromised

The contact owns a 2026 GMC Terrain. While driving at 28 MPH, the RPM became elevated to over 3,000 RPM. There was no warning light illuminated. The contact immediately pulled over and then resumed normal operation after the failure. The vehicle was taken to the dealer to be diagnosed; however, no cause for the failure was found. The contact was advised to bring the vehicle back to the dealer if the failure reoccurred. Approximately one week after the initial failure, while driving approximately 30 MPH, the transmission unexpectedly downshifted to L2. There was no warning light illuminated. The contact pulled over and restarted the vehicle, and the vehicle was taken back to the dealer. A diagnostic test was performed, and the contact was informed that the transmission needed to be rebuilt. The manufacturer was notified of the failure and was provided a case number. The vehicle remained with the dealer unrepaired. The failure mileage was approximately 1,300.

The contact owns a 2026 GMC Terrain. The contact stated that there was an abnormal clunking sound coming from the front driver’s side suspension while driving over bumps in the roadway, and while braking and turning the steering wheel. No warning lights were illuminated. The vehicle was taken to a local dealer, where a test drive was performed; however, the dealer was unable to determine the cause of the failure. The vehicle was not diagnosed or repaired. The manufacturer was not notified of the failure. The approximate failure mileage was 14.

Vehicle “wobble” under moderate acceleration and in corners, can be felt in the seats and steering wheel.

Purchased NEW 2026 GMC Terrain Elevation, and it came with NO User Manual. I was told by the dealership (Al Serra GMC in Grand Blanc Michigan that i could either purchase one for $50.00+ dollars, PLUS TAX & $25.00 SHIPPING, or d/l it via the infotainment system in the car, WHICH DID NOT WORK! Talk about [XXX] A VIETNAM VET!!! We are both [XXX] old & need a manual, so bought a reproduction of the original via eBay for $50.00. At least GM could reimburse the cost of the manual… INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

I was driving (roughly about 30 MPH) when my automatic braking kicked on and caused my tires to squeal to a halt. There were no other cars around me (thankfully) - otherwise I would have been rear-ended. Right before it stopped, it flashed the warning lights for a quick second. I wanted to report this issue in case others are experiencing the same problem and to hopefully help prevent it from happening to someone else. Very scary and could cause a serious accident. I turned off all of my automatic brake settings after the incident, as I believe it is faulty and don't want to risk it happening again.

Car was off and parked and randomly caught on fire. Completely totaling the car

The system that failed was the brakes, The car is availble for inspection. My saftey and others was put at risk due to not having brakes to stop. The problem has been confirmed by a dealer as a master brake cylinder failer The vehicle has been inspected by the dealer. There were warning lamps, message and other symptoms of the problem prior to the failure. They first appearead on December 4 2025

The vehicle has been taken to the dealership at least 4 times. Each time for the same reason: when driving at 65 or higher, it sounds like it's on a flat. My screen also glitches when foot is taken off the break after a stop. The service advisor told me that there was a shortage of mechanics and asked me to bring it back next week (this is the response I have gotten each time). I have asked for a loaner twice and was told that there were none available. Therefore, I had to pay $40 to uber to work. Today, I said that I couldn't come back because it's the same issue and I have to work next week. He then let me speak to a service manager. The service manager drove it (with me in the passenger seat) and heard the sound. He noticed that it was not all of the time and that my steering wheel was a little shifty. When it was finally "fixed" (tires being rotated and some steering update), I was told to come back if I hear it again. I left at about 2pm and heard the sound again, as well as my screen began to glitch when I get off the break after a complete stop. I took a video of the glitching and took it back for both issues. I was told that some bolts were tightened and some update was done to the screen, and if I hear it again come back. On my way home at 4:35pm, the issues were not resolved.

The contact owns a 2026 GMC Terrain. While drying the vehicle after it was washed, the contact became aware that the middle section of the vehicle was loose. The vehicle was taken to the dealer. The dealer informed the contact that the part to repair the vehicle needed to be ordered. The contact was awaiting a response from the dealer. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 3,000.

I have brand new GMC Terrain 2026, I leased dog on Aug 4th 2025. After one week into driving the vehicle, OnStar, GPS NAV stopped working and the Emergency calling is not working. All features related to locating the vehicle through OnStar or through google stopped working, in addition to SoS not working. I took it to the dealership they said the Telematics module needs replacement.

Master cylinder , less then 1000 miles was pulling out of a parking lot and the brakes went out

Very soon after purchase vehicle developed a front end shake and continued to get worse. This happens when pulling out or in stop and go traffic this varies from in intensity and sometimes it can be quite violent shaking the whole vehicle. The car has been to a GM dealership for this problem 3 times now. The first time 9/8/2025 replaced rear axle, the second time 10/20/25 both front axles were replaced. The 3rd time GM engineer Paul Koerner said they are aware of this problem but there is no repair until it is further investigated this was 12/10/25. As of this time there is still no repair but a bulletin has come out document #7036661. This states the customer should continue to drive vehicle I now have 7600 miles on it and it continues to shake every time I pull out. There seems to be no repair in sight and I’m concerned something will finally fail maybe causing a serious situation and about the unknown damage this is causing to the vehicle. I have written a letter to GM corporate about my concerns and asked for vehicle replacement to no avail. I have all the repair orders and documents and would be glad to give them to you as I have tried to upload them and it seems to work but won’t let me continue.