Something weird is happening to my 1993K Volvo 940 2.3 turbo estate. I'd be grateful for your help in identifying what has gone wrong and how to put it right - if that's possible and economically worth doing. The car has suddenly started to extrude from the exhaust pipe a continuous ribbon of fine hair-like material, a sort of white/silvery colour with dark edges. The ribbon is about one inch wide and very soft to the touch: rather like a very fine horse's mane. In its way it looks quite attractive, but not when it's issuing from the back of the car as you drive along. I've owned the car from new and it has done just over 163,000 miles.