Alert; You don't have to screw with bumper
 

Just wanted everyone to know that it's tough drilling that first screw into that clean bumber. Well, you don't really have to. Turns out that the holes in the newer mercedes bumpers accept a plastic rivet (I purchased at lowes).
Remove the rivet from it's base and press into the bumper. Might want to use washer on standard plates, but I drilled a small enough hole on my euro plate so no washer was needed.