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/Motiv Port Fuel/Meisterschaft Race/Berk Resonated/ER CP/Synapse/VRSF FMIC/Rob Beck PCV Valve + Cap/ST Coilovers/M3 FCA + Tension Rods/M3 Subframe Bushings/M3 FSB/AA Strutbrace/DINAN Camber Plates/Apex ARC-8/Project Kics/VAC Hubs/Rogue Transmission Mounts/Alpina TCU Flash/Icarbon/Kerscher/BMW Performance