2026 GMC Terrain Problems

On the evening ofXXX, at approximately 6:00 PM, I was driving this Avis rental vehicle on a highway in [XXX] at normal highway speed, below the posted limit, with my foot on the accelerator. The forward collision warning and automatic emergency braking system activated and applied the brakes hard. There was no vehicle, pedestrian, obstacle, or hazard ahead of me, and no vehicle behind me or beside me. The roadway was clear and dry. The sun was low in the sky, and the vehicle was crossing a metal expansion joint on an overpass at the moment of activation. I believe the low sun angle, the expansion joint, or both caused a false object detection by the forward-facing camera or radar. The service brakes themselves functioned correctly. The failure is in the forward sensing and decision logic, which commanded a braking event with no object present. The deceleration was severe and unexpected. I sustained sharp pain in my neck and shoulder. Had any vehicle been following me, this would have caused a rear-end collision at highway speed. There were no warning lamps, messages, or other symptoms before the event, and none afterward. I had driven the vehicle for seven days with no prior indication of a fault. I exited the highway immediately and drove back to the rental location on local streets at low speed because I no longer trusted the vehicle. I returned it the following morning when the Avis office opened, more than a day early, and reported the defect. Being a rental vehicle it was not available to me for inspection. The rental company has advised that it was taken out of fleet for inspection after my return, that there are no open recalls on it, and that it will not release internal service records to me. I do not know the outcome of that inspection. To my knowledge the fault has not been reproduced or confirmed by a dealer, independent service center, or manufacturer representative. No police report was filed because no collision occurred. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S

a failing telematics module on your 2026 GMC Terrain is causing network corruption, leading to an erratic speedometer and loss of driver assistance systems while driving.

Avis Rental. Vehicle simply shut down while driving and would not re-start. Vehicle could NOT be put into neutral to move from roadway. Emergency services vehicles had to remain on site awaiting tow vehicle. Very dangerous situation.

This vehicle was bought new and is a NEW 2026 GMC TERRAIN DENALI with less than 5,000 miles at this time. It is a continuous event and not a specific failure date, but began soon after purchasing. The specific parts are UNKNOWN. It could be tires, wheels, steering parts (CV JOINTS, CONTROL ARMS ETC) or possibly transmission. I took it initially to the purchasing dealership and they took it for a ride and just dismissed the problem without investigating. Several days later I called and talked to the person who sold me the SUV and was told either him or service manager or both would call me, but neither did so. They were to set up a return date. After this insulting experience I decided to take it to a Cadillac dealer that I have had great experience with in the past. They took it for a ride and did experience the problem and investigated what they thought could be causing the SUV to wobble, shimmy, or shaking sensation. This Cadillac dealer said there investigation showed nothing wrong and returned the vehicle to me and said nothing could be done unless GM gave them permission. Next I wrote to the service manager expressing my disappointment in nothing being done and my disappointment in General Motors. There is a Service Bulletin (Document ID: PIT6466). This makes four efforts on my part to get satisfaction with this 2026 GMC TERRAIN DENALI and how it is not fun to drive and there is anxiety on the safety of the vehicle when being driven. *Now for the problem I am experiencing with this 2026 GMC TERRAIN DENALI. There is the sensation of a “wobble, shimmy, or shaking” under low to moderate acceleration when going straight or turning. It could be tires, wheels, steering parts or power train. It is difficult to tell. Sometimes the sensation is as if the wheels will fall off. This is an awful feeling and gives you the feeling the SUV is not safe and it is not fun to drive at all.* Why do I have to drive a brand new expensive SUV and feel unsafe and not enjoy do so?

My vehicle is making a squeaky sound/noise when breaking and getting louder. I took it in for service and they couldn’t seem to find the issue. It’s coming from the front end of the vehicle

Shimmy, shake, wobble, after TSB 26-NA-109 repair, replace front springs, vehicle feels less stable at highway speeds. The initial condition, Shimmy, Shake, Wobble, under moderate acceleration, still exists after last repair attempt.

a failing telematics module on your 2026 GMC Terrain is causing network corruption, leading to an erratic speedometer and loss of driver assistance systems while driving.

Avis Rental. Vehicle simply shut down while driving and would not re-start. Vehicle could NOT be put into neutral to move from roadway. Emergency services vehicles had to remain on site awaiting tow vehicle. Very dangerous situation.

My vehicle is making a squeaky sound/noise when breaking and getting louder. I took it in for service and they couldn’t seem to find the issue. It’s coming from the front end of the vehicle

ABV came on. SCR alerted I needed service. On a 25 mph road I no longer could brake randomly

This vehicle was bought new and is a NEW 2026 GMC TERRAIN DENALI with less than 5,000 miles at this time. It is a continuous event and not a specific failure date, but began soon after purchasing. The specific parts are UNKNOWN. It could be tires, wheels, steering parts (CV JOINTS, CONTROL ARMS ETC) or possibly transmission. I took it initially to the purchasing dealership and they took it for a ride and just dismissed the problem without investigating. Several days later I called and talked to the person who sold me the SUV and was told either him or service manager or both would call me, but neither did so. They were to set up a return date. After this insulting experience I decided to take it to a Cadillac dealer that I have had great experience with in the past. They took it for a ride and did experience the problem and investigated what they thought could be causing the SUV to wobble, shimmy, or shaking sensation. This Cadillac dealer said there investigation showed nothing wrong and returned the vehicle to me and said nothing could be done unless GM gave them permission. Next I wrote to the service manager expressing my disappointment in nothing being done and my disappointment in General Motors. There is a Service Bulletin (Document ID: PIT6466). This makes four efforts on my part to get satisfaction with this 2026 GMC TERRAIN DENALI and how it is not fun to drive and there is anxiety on the safety of the vehicle when being driven. *Now for the problem I am experiencing with this 2026 GMC TERRAIN DENALI. There is the sensation of a “wobble, shimmy, or shaking” under low to moderate acceleration when going straight or turning. It could be tires, wheels, steering parts or power train. It is difficult to tell. Sometimes the sensation is as if the wheels will fall off. This is an awful feeling and gives you the feeling the SUV is not safe and it is not fun to drive at all.* Why do I have to drive a brand new expensive SUV and feel unsafe and not enjoy do so?

Car aggressively shakes and steering wheel shakes / jerks itself side to side when accelerating. Getting worse with time. GMC has it as a known issue but has been for months. Problem is getting worse the more it is driven. GMC says it is “safe”.

This vehicle was bought new and is a NEW 2026 GMC TERRAIN DENALI with less than 5,000 miles at this time. It is a continuous event and not a specific failure date, but began soon after purchasing. The specific parts are UNKNOWN. It could be tires, wheels, steering parts (CV JOINTS, CONTROL ARMS ETC) or possibly transmission. I took it initially to the purchasing dealership and they took it for a ride and just dismissed the problem without investigating. Several days later I called and talked to the person who sold me the SUV and was told either him or service manager or both would call me, but neither did so. They were to set up a return date. After this insulting experience I decided to take it to a Cadillac dealer that I have had great experience with in the past. They took it for a ride and did experience the problem and investigated what they thought could be causing the SUV to wobble, shimmy, or shaking sensation. This Cadillac dealer said there investigation showed nothing wrong and returned the vehicle to me and said nothing could be done unless GM gave them permission. Next I wrote to the service manager expressing my disappointment in nothing being done and my disappointment in General Motors. There is a Service Bulletin (Document ID: PIT6466). This makes four efforts on my part to get satisfaction with this 2026 GMC TERRAIN DENALI and how it is not fun to drive and there is anxiety on the safety of the vehicle when being driven. *Now for the problem I am experiencing with this 2026 GMC TERRAIN DENALI. There is the sensation of a “wobble, shimmy, or shaking” under low to moderate acceleration when going straight or turning. It could be tires, wheels, steering parts or power train. It is difficult to tell. Sometimes the sensation is as if the wheels will fall off. This is an awful feeling and gives you the feeling the SUV is not safe and it is not fun to drive at all.* Why do I have to drive a brand new expensive SUV and feel unsafe and not enjoy do so?

Car aggressively shakes and steering wheel shakes / jerks itself side to side when accelerating. Getting worse with time. GMC has it as a known issue but has been for months. Problem is getting worse the more it is driven. GMC says it is “safe”.

The contact owns a 2026 GMC Terrain. The contact stated that while driving 10 MPH and pulling into a parking lot, the vehicle was shifted into drive(D) and the driver’s door lock unexpectedly unlocked. The contact stated that on another occasion, a passenger in the front passenger’s seat noticed the same failure with the passenger’s side door lock. The vehicle was taken to the dealer, where it was not diagnosed or repaired. The contact expressed concern that the failure was hazardous and posed a safety risk because the doors could open while the vehicle was moving. The manufacturer was not made aware of the failure. The failure mileage was approximately 2,500.

The contact owned a 2026 GMC Terrain. The contact stated that while her husband was driving on a perpendicular road at an undisclosed speed, entering a highway, the driver yielded; however, a truck in the median was attempting to cross the highway during oncoming traffic, and an oncoming vehicle crashed into that vehicle, causing the truck to crash into the front of the vehicle. The front air bags deployed as intended. The contact stated that an electrical fire started under the center console, and the driver’s shirt was burned by the fire. The Fire Department was on scene and removed the contact from the vehicle; however, a fire report was not filed. An off-duty sheriff witnessed the crash and assisted in removing the contact husband from the vehicle. The driver was taken to the Emergency Room for neck, arm, and wrist injuries, bruises, burns, and scratches. The contact was unsure of how the fire was extinguished. The contact mentioned that the smoke emitting was carbon monoxide-related. The vehicle was towed to an impound lot and was deemed a total loss by the insurance provider. A police report was filed. The dealer and the manufacturer were notified of the failure, and there was a pending inspection on the vehicle. The failure mileage was approximately 6,300.

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

At 12,000 miles removed old air filter found grass under air filter

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.