Interesting because the W221 MOST diagram has the VCM input connected to the phone control unit output. Why not the opposite order if it helps auto detection?

PS. I did assume that swapping microphones would not matter (much?) but I still find it odd that the wiring at the car as from the factory did not match that from WIS. I followed the WIS diagram when connecting mic wires to the VCM plug,

Comparing the W203 and W221 wiring diagrams, microphones are swapped like 1, 2, 3, 4 on one to 4, 3, 2, 1 on the other. This still keeps them in an array while my car had microphones in the sequence 1, 3, 2, 4, which I believe might affect the noise cancellation algorithms.