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 FBO N54 Alpinweiss/Coral Red/Meisterschaft Race/Berk Resonated/Macht Schnell 3"/ER CP/Synapse/VRSF FMIC/FFTEC LPFP/HFS-4 DO Stainless Lines/BMS DCI/BMS Thermostat Delete/Rob Beck PCV Valve + Cap/BMS OCC/PTF E50/ST Coilovers/M3 Front Control Arms + Tension Rods/M3 Subframe Bushings/M3 FSB/DINAN Camber Plates/Apex ARC-8/Project Kics/Macht Schnell Studs/VAC Hubs/Rogue Transmission Mounts/Alpina TCU Flash/Icarbon/Kerscher/BMW Performance