Yet another question. Today for the first time a white P on a blue background appeared on the dash, I think just below the C/S/S+ drive mode symbol. It went away after a short bit, but came on after I started the car again. I cannot find any reference to it in the manual. Any thoughts?

Thanks

 

In my wife's car the P usually means that there is a suitable sized parking available (part of parktronic)

 

Check around page 183 of your manual for a description of all the systems. The P is telling you the sensors on the side of the car detect a suitable space. There is a switch on the dash with a P on it as I recall. This shuts this feature off.
If you do not have a manual you can get one to download at MBUSa's site.

 

RTFM: Download here if you lost it (PDF versions are searchable) --> https://www.mbusa.com/mercedes/servi...wners_manuals#

 

The P is the car scanning for suitable parking spots at low speed (I think 11 mph?). The P with a white arrow indicates it found one and you may begin "park assist parking" by putting the car into reverse and using the steering wheel to accept/decline.