My 2026 GMC Sierra has an oil-canned roof from a touchless car wash because the sheet metal lacks structural rigidity. This caused the roof to buckle and caused a permanent fold in the roof of the truck. There is already documented issues for this exact problem on the newer GMC Canyons and Chevrolet Colorado mid-sized trucks. Bulletin for reference NHTSA Official TSB #23-NA-209 PDF. I leased the vehicle on 6/19/2026 and this happened on approximately 7/7/2026. The vehicle only has 1,480 miles on it as of this date.

While driving vehicle the engine lost power and shut off in traffic. There were no warning signs of issues at that time. The dashboard went blank and then reappeared and the truck was in park. after that the truck would not shift gears. The truck was towed to the dealership and found to have had catastrophic engine failure.

No sound at different times. No way to reset issue. TSB issued May 14, 2026 for known issue. As of July 6, no estimate on repair. Blinkers make no sounds, Onstar can call but you cannot hear them. In event of accident, no communication.

I purchased this new full-size heavy-duty pickup, and at purchase the selling dealer installed a 3-inch suspension lift kit with 37-inch tires on 22-inch wheels as a paid dealer upfit. The lift kit manufacturer publishes a maximum tire size of 35 inches on a 20-inch wheel for this kit; the tires and wheels the dealer installed exceed that spec. The lift manufacturer confirmed directly that they would never approve exceeding the 35-inch tire / 20-inch wheel recommendation. The dealer's assistant manager confirmed that NO calibrations of any kind were performed after the lift and 37-inch tires were installed, and said nothing is recalibrated when a lift is done with 37-inch tires. This vehicle is factory-equipped with forward collision alert, automatic emergency braking, front pedestrian braking, lane departure warning, and automatic high-beam control. These crash-avoidance systems rely on forward-facing camera and sensor aim, which depends on ride height and suspension geometry. A 3-inch lift with 37-inch tires materially changes that geometry. With no calibration performed, there is no assurance these safety systems are aimed or functioning to spec. The truck was also never aligned after the lift and the tires are cupping. The headlights were never re-aimed for the higher ride height, and the speedometer was never recalibrated and reads inaccurately. The oversized tires also contact the body. The left front tire has torn into the front fender, the fender well is misaligned, and it is forcing the lower front edge of the driver's door out of alignment. The dealer's only proposed remedy is to keep cutting the fender wells; the trimming already done has exposed electrical wiring behind the wheel well to mud, water, and road debris. I am reporting this because the assistant manager's statement suggests it may be the dealer's standing practice—other customers may be driving lifted trucks with uncalibrated crash-avoidance systems without knowing it.

The contact owns a 2026 GMC Sierra 3500. The contact stated that while driving at 35-40 MPH on the interstate and towing a loaded trailer, the vehicle experienced reduced braking performance. No warning lights illuminated. The local dealer was contacted and informed that the brakes performed differently. Additionally, the dealer stated that the transmission was not downshifting. The vehicle was not diagnosed or repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 500.