Right I went to test drive an M3 yesterday, all seemed well. Full service history, good spec, decent mileage etc. However during the test drive I could hear a strange noise around 3000-4000rpm, almost a quick clicking/buzz hard to explain, seems to be coming from the engine I think. Now the guy who took my out said he couldn't here anything. Today it went for an inspection with this guys mechanic, who said he couldn't hear anything and couldn't see anything wrong. Now I'm not sure what to do, I definitely heard something that didn't seem right, but obviously I'm no mechanic! Any opinions?