Hi jgibbons, there were a few different bumper colors used throughout the years. Any Mercedes body shop can mix and match the paint for you based on the color code. If you post your vin # XXXXX can tell you what color you have.
I know it is 172 for the body, but I can't tell what color code the bumper is.
Good morning jgibbons, your bumper color is Mussel Grey. The Mercedes paint code # XXXXX 7176. A body shop can use that code to match your paint. I've attached the color footnotes for your car that apply to the various exterior paint color codes below.