The worst sound my E39 had was the creaky fold down rear seats. Toss it into a corner, and you hear the seats shift...quality.
The other noise was a sometimes blah note from the M52; it sounded like a sewing machine when you drove next to a wall with the window down. Oddly enough though, it sounded fantastic from the inside, and great out the back. But from the side, it sounded really weak (which is was
).
