Lol welcome to the 1 series, they squeak and rattle big time. On the passenger side i get a light rattle from the glove box and a pillar under load or when driving on a rough surface. Im not sure about a metallic sound, but if youre just talking rattles..."it is what it is". The trim that runs along the dash has also been known to have rattles underneath it as well.
E88 N54 Alpinweiss/Coral Red/Motiv HTA 3586r Tial .82AR/Other stuff...652WHP
F30 N55 XDrive EBII