I can't comment specifically for BMW, but I was told the K&N would void my warranty in my Dodge Cummins Diesel. It did not meet the 97% filtration that was required by Cummins. But K&N had a filter for it. I am sure that they will have one available for the BMW diesels for the European market.

As a side note, had one on my older Cummins diesel. I was able to get about 10k miles on a premium paper filter before the vaccum guage let me know that filter was full. The K&N went 30K and vaccum guage didn't move. I did not think that it was filtering as good IMO.