fueling systems prime when the car is unlocked, and the water pump flows upon shutdown to cool things down. If you sit inside the car when it has been turned off, the CD player unit makes all sorts of noises. I have no idea what that’s all about. I've sat in N54 powered E9xs, E6Xs, and E8Xs, they all do it.
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/Apex ARC-8/Project Kics/Macht Schnell Studs/Rogue Transmission Mounts/Alpina TCU Flash/Icarbon/Kerscher/BMW Performance/Cyba