Originally Posted by 4RD H8R
If you mean this piece, it is a pressure relief vent. It is there so when you close the doors or the trunk it is easier. With the tighter seals modern cars have, it gives the air someplace to escape when closing things. I can't think of any late model cars that don't have them.
As far as drone, I don't think it would make any difference.
That's it. Thanks for the explanation. It makes sense.