The Mercedes-Benz S600 Guard is a V12 powerhouse armored to VR9 spec, meaning they can shoot at it, blow it up or throw nasty gas canisters around it all day long and you'll be fine inside, with a glass of champagne at hand.
I love how a certain part of the press release is about how discreet the S600 Guard is on the move, looking almost identical to the standard S600. Right! That's very practical indeed, making sure the guy with the RPG doesn't know which black Merc to shoot at, but as far as I can tell, the people who buy these aren't necessarily European diplomats and a black S600 will stand out in a third world country anyway. Also, if you travel in a convoy of three, they'll most likely shoot at all of them.