Just over the border in Passaic County (not far from Ramsey, easy off Route 287), in Pompton Plains is Brothers Mercedes. They have a good rep, I called them to get some quotes and their prices were reasonable.
Some background from
http://www.brothersmercedes.net/company.htm:
"...family-owned and operated company was started in 1975 in Pompton Lakes. The owner, Ahmet Hacioglu, was factory trained in Germany, Turkey, and New York. Before creating Brothers Mercedes with his brother, he was the shop foreman at Mercedes Manhattan. His long list of experience qualifies him as a master mechanic, and his work is superb and precise. As the company grew he moved the company to Pompton Plains. Our company still resides there today"