Someone please help this man.
I have a C-Class, but maybe I can provide some assistance. I have noticed that under my car. The lower part of the car is made differently, where you're supposed to jack the vehicle. If there aren't little "entry" holes on the sides of the vehicle, at the bottom, then simply go outside with your Mercedes parked as normal, look under it and you should notice places where you can jack the vehicle.
One of my girlyfriends has an M-Class, so I'll look under hers when I see her later on. She's still in class; I'm done for the day. So when she comes over I'll look under it and thru her manual.
Or I'll do the unthinkable and look under a neighbors M-Class when I see one roll-up, in order to find out. There are like 4 of them on this street, haha so you're in luck.
If nobody has helped you out by then I'll definitely have something.