Check your exhaust hangers
I just replaced my two middle rubber/fabric exhaust hangers. They were broken yet had a somewhat intact appearance. The broken hangers allowed my exhaust to drone/vibrate a bit and I had a slight hard to find rattle. Both are gone now. Might be worth a check. My indy says the all rubber rear hangers seldom fail.
Thanks,
1995 525i Auto, M50TU 2.5L, EAT chip, 1/95 build, USA, 205/65/15 tires, ASC+T, HID, lumbar, EC Mirror, BMW Alpine 5 radio with BMW-Pioneer CD Changer, abt 236k miles, Oxford Green/Parchment