I'm having a message pop out on my R171's SLK display saying that i must perform Service D in xx nr. of days. Anyone know what service D is and what they change/check?

Thanks

 

The Mercedes computer classifies the 1st service as A, 2nd as B etc.

So that will be your car's 4th service I believe. That is how they were configured on my ex-SL's

 

I see but do you happen to recall what they change on it? I found an E class owner from a diff. board saying that all they do is check the fluids and change the polen filter (no big deal like full oil and filter change, brake pads or anything like that).