I've got a '97 M3/4a with 178k miles on her... still runs like a champ. This morning I brought her in for her 'regular' replacement of the rear shock mounts. You can tell they need to be replaced if you hear a 'clicking sound' from the rear corner, and if you push down on the corner of the trunk you can hear the sound click sound.

Well... turns out the rear shock mount wasn't the problem, but the sheet metal that the shock connects into:




I'm still going to drive this car until the wheels fall off...