I've go a 2002 audi a4 tdi 130bhp 96kw, with FASH. It was 'chipped' by the last owner (a plug in, is all it was described as) at around 75,000 miles and is currently at 90,000 miles, but chucks out masses of black smoke. When it went in for the last service in audi i asked if this was normal and the guy said it was normal, but i've never seen a car put out so much 'soot'. I assumed this is unburnt fuel, but with it being so economic i'm confused. my last car was a 306 diesel (non turbo) which was really good on fuel but really slow. but the audi seems to be amazingly quick yet has better economy, doing 60+ mpg on a run? Should i be concerned?