Hi mate,
Thanks for the reply.
It is indeed a BMW AUC. I have been listening to the turbo more and think its the turbo noise when the revs drop. I've found a video on YouTube of a 640d.
0.41-0.48 seconds you can hear it when the revs drop. Mine makes the same noise.
Thats what I was thinking, guess i'll have to get it booked in as its still got the balance of the new car/approved used car BMW warranty.
Nevertheless loving it so far, a cracking car!