I see some black dot on the rear rotors. Should I be worried? What is that?

- They seems symmetric, like apart from each other 120 degree
- Both left and right rear rotor has them, same spots
- it is new car, just 8000km-ish
- my GLC has sport and night package
- One of them has a bit indent on it, is this wear indicator? I am just guessing.

I noticed these on my GLC too and I asked the MB Service Manager what they were. I believe he said they may be used in production to hold the rotors in a particular position by the automated robots. In any any case, I don’t think they are anything to be worried about. But they are definitely noticeable and sort of look out of place.

And they may very well be wear indicators. Once they’re gone maybe your rotors are getting too thin. I didn’t pursue it, but please let us know if you get an answer from your MB service guys.

It's wear indicators .

Right. They are also on the front.

Yes, you should be very worried. Seriously though, they are wear indicators. You can take it easy now.

you are being hypocritical. Why should op be worried? At least you are right on the wear bit.

It's sarcasm. Hello.

it's hard to understand tone from text. So sorry.

Nothing to apologize for. all good.

I am **** off.... just kidding.

But proof it it is wear indicator if you think so, as I think so as well. I never seen indicator on the rotor though.

me neither. I think it may be something else but my glc 2019 had it also, no sport or night package.