17Jan2023. 2018 GMC Sierra 3500HD Denali. Northbound on I37 near Three Rivers, TX. Speed approx 75 mph. Temp approx 55F. Wx conditions, 1/2 mile vis in fog. Traffic, zero vehicles ahead, one vehicle approx 100 yards behind. Time approx 0815. No overpasses encountered. Cruise control engaged. My son and I were talking when we both heard a sound us above resembling ripping cloth lasting approx 1/2 second immediately followed by a loud explosion followed by the sound of fragmented clinking. The rush of wind noise followed as we could hear pieces of glass continue be taken by the slipstream. I was able to immediately deduce that the sunroof had catastrophically failed. I never use the sunroof or even open the slider so luckily it was closed as usual and no glass fell into the cab and no injuries were sustained. My son and I began to look around us while continuing down the highway to see if an object could've caused this. With no vehicles in a position to have flung a rock or other material and no overpasses in the area, we concluded it must've been a defect. I took the next exit and stopped in a gas station parking lot. We exited the truck and visually inspected the roof. The glass was indeed shattered. Further, the glass had appeared to failed outward as the remaining glass was directed away from the cab. There had been no prior indications of impending failure. There were no warning lights and the police were not called. Had a vehicle been close behind the outcome may have been worse as it would've been showered with debris. The vehicle is under warranty but GM has declined coverage, claiming it must've been a rock or something, even though that would've been impossible given the circumstances.

- Corpus Christi, TX, USA