It left the factory with a Bosch, and that's always what I use on all of them. And it was great up until just a couple years ago. Because, you could still buy the exact same Bosch filter, made in Spain, that all the ALHs, BEWs, and BHWs used from the factory, regardless of where they were assembled.
Now, Bosch jumped on the cheapening band wagon with these, and they are made in Tunesia. Which is probably better than China, but they clearly are not the exact same as they once were. However, until I see something that gives me cause for concern, I'll keep using and recommending them.
However, Mann, Mahle, and Hengst are all excellent choices too. Mann is who supplies the BRM cars, and many of the CR cars before UFI took over.
