Since your car is relatively new, you have wear sensors and unless the pads have been replaced already with cheap pads (no hole for the wear sensor) or the sensors were not replaced/reinstalled your pad wear is within spec unless it is lit. Yellow light with a circle in the middle and two dashes on either side at the 11 and 2 oclock position.

Mercedes brakes are notorius for squeaking, even the newer ones. You can try brake cleaner but its considered "normal" as aggravating as it can be.

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1981 300TD
2005 C55
2004 E500
1999 ML430
1992 400E
1998 C43
2001 SL500
1988 300SEL
1986 190E 16V
1991 190E 2.6