Different behavior w/o making changes
Mine's a 2016 E350, w/ everything stock & unmodified.
Assyst
It used to tell me when service is due in terms of time (ie "in 187 days").
But now it's presenting the service reminder in terms of distance ("in 8000 miles").
CD Player (Yes, I'm old school)
It used to resume playing where the music stopped previously, even when changing between Media & Radio.
Now it would always start playing from the beginning / track 1.
Navigation
I could've sworn when the GPS audio comes on near a turn, the radio music would stop.
Now the GPS & radio audio would overlap w/ each other, making it hard to hear the GPS directions.
The Assyst & CD Player behavior change just occurred in the last few weeks.
The GPS audio happened a lot earlier, like last year.
2014+ I believe depending on use it would show days or miles. If you have been driving your car a lot lately then it will move to miles, if you don't drive it a lot it will display days.
My 2012 has always done miles because I have use it at least 9k a year.
I don't remember CD thing as I mostly used to use SD Card to play music




I choose to ignore time-forced schedule as that was forced by US lawyers and keep paper trail for oil change, so can drive over 10k miles on oil regardless the time.
As for volume adjustment, that took me well over a year to figure out.
If you want navi volume adjusted, you have to do it while navi is speaking, otherwise you adjust the radio.





