OK have been searching the forums and Google but have not found any good advice:

I am looking to service my somewhat older BMW M3 (E46 from 2001). I would prefer an independent trusted garage as servicing a 10+ years old car at an official dealership probably does not make sense.

The M-series BMWs have their own quirks and require their special oil so I would want someone who specializes in BMW and the M-series.

This is a bigger service (oil change, brake fluid change, coolant change, oil level sender seems faulty and should be replaced).

I live in Zurich. Something across the border in Germany would be fine as well (and probably quite a bit cheaper).

Any garages known to be specialized in M-cars and something people here have had positive experience with?