Think of it like this:
Would you have rgd it had mercedes never exsisted?
Nope. Its still a trademark infringement, but if you are confident of taking on Mercedes lawers feel free to crack on. I know for a fact any half competant domainer would not touch anything that could be easily be served a cease notice.
Edit:
I could say the same about a domain I own: hooverrobots.com. I could say I am trying to attract a sub market, but ultimitly I am still using a trademark either way you cut the cake.