I do agree that means mercedes-benz but it's some sort of a slang and not really good one.

Мercedes-benz.

либо слэнговое название машины мерседес-бенц либо коммуна во Франции.

Don't bother yourself with this word :))) I even didn't know it.

It is funny in one way - it sounds very similar to рысак, which means a trotting horse:) So if someone looks at a Mercedes as their horse...:) I don't think the word "Мерсак" is used much, though.