Driving my vRS last night, I noticed a sort of raaasssppp-raasspp-rasp sound when driving in traffic and slowing down, it tended to start as I (gently) applied the brakes, but continue for a while afterwards. It was definetly coming from the rear on the passenger side, and sounded to me like the brakes (they do rasp slightly from the rear sometimes anyway). It was consistent yesterday; but doesn't seem to be occuring today.

Any ideas what it might be?

Maybe a stone caught in between the disc and pad ....had it happen to one of my cars before

If its a tinny rattly sort of rasp - it could be a stone stuck where the exhaust heat sink is - or your heat sink has come loose.

HTH, D

No, it's more of a grinding noise. I'm taking in to the dealer to be checked out in half and hour so I'll let you know what they think.

Lodged stone. I've had this before when a stone lodges between the disc guard and the disc itself. Really makes an awful noise. Best way I found to dislodge one is to either reverse really fast, or bash the disc guard with a screwdriver to knock it out.

It seems it worked itself out this time. By the time I'd got it to the garage the noise had long gone; they took a look took it out for a drive and agreed with your diagnosis of a lodged stone.