I'm not sure how Sachs performs for Bimmers, but on a VW Golf I had, I thought I'd save money and buy a Sachs, and it was crap. It lasted 2 years and 75 000 km, then I put an OEM from VW and it went the rest of the life of the car which was another 220 000 km when I sold it and as far as I know the next owner used it until he parted the car out 3 years later!!!! Just my two cents, you might save a little at first but it's going to cost you more in the long run.
Honda Civic EX - Parkway Honda Company car
BMW 325I E30 Chumpcar Race Car
VW JETTA 1.8T WAGON Family Hauler (sold)
HONDA ODYSSEY 2nd Family Hauler (sold)
BMW 540iT M-Sport (New Family Hauler)