I think it is the same kind of key blank as my 88' 300e. I went to a good locksmith shop. It takes a special machine and they will not be able to do it at home depot. It cost me $25 bucks. Not Cheap but cheaper than loosing the key and having to have a key made or ordered from the dealer; lots more cash.
I gaurantee I don't try to use my merc key for a screwdriver or bottle opener.....I use the house key....its cheaper to break a window.