One problem related to sun roof has been reported for the 2013 Mercedes Benz GL450. The most recently reported issues are listed below.
At 9:22am on the morning of January 2, 2019, my SUV was parked in my driveway. It was overcast, calm conditions, and around 52�. I unlocked my vehicle, got in, started the engine, and closed the driver's door normally. One second later, I heard an explosion as the sunroof exploded. There was no evidence of anything haven fallen on the vehicle nor any evidence that anyone had tampered with my SUV. I had last driven the vehicle the afternoon of December 31, 2018 in conditions similar to those described above. I have no recollection of my vehicle being struck by any objects in recent years. This was a sudden and very unexpected occurrence.