not really an answer, but I don't use the built in
1. too much head turn from attention to the road to see map
2. a lot of times the central screen is unreadable due to various reflections etc.
I transferred my TomTom from the previous class C, it sits in same easily viewed place in front of steering wheel, shows my speeds vs. posted limits (sometimes erroneously)
as in previous vehicle I routed power up to a 12V socket in that area of dash, a fairly easy procedure since the A-post cover pops off easily, at same time did a better job of securing the mike and camera cables in the A-post