I don't know if anyone else has had this problem yet but my son noticed that the passenger side makes a rattle almost sound on highways. Anyone else experienced this. We tried closing the window. Should we bring it to the dealer
check that the portion of the latch that's on the car body has all it's bolts. Mine was missing one and creating a lot of rattle. Noise went away when the dealer put the bolt in.
Mine will make a rattle when the seat belt buckle is against the door and seat. I assume this isn't the case because your son was wearing his seat belt.