If you are part exchanging for a new Mercedes; you will obviously get less for your old car as that will in effect fallen in value by 20% in the near future.

I suppose if you were considering changing your used BMW for a new Mercedes, now would be the time before BMW reduce their prices which inevitably they will do.

With the 1.20 chf to eur is this still in place?

Probably, it was 1.60 not so long ago.