[S90]

Recently my car developed an annoying rattle, it appeared to be from the rear, but you know how rattles are.

Anyway, went out one day to try to figure it out, turns out the cover over the passenger side rear seatbelt buzzes against the fixing below. Pop it off, may as well do both sides, stick some felt tape in and voila, issue resolved, plus a few other noises gone!

Thought this may help anyone with an S90. The covers just pull off.