I know what you're talking about now. You mean the vents between the inside and outside rotor surfaces, not the cross drilled or slots.

I'm trying to understand the need for brake improvement for any Mercedes since they started using four wheel disks. Barring an all out racing situation, there's plenty of brakes on these cars.

I've hauled my 300E down from 140 MPH before in amazingly quick, controllable style. I don't think any of my diesel MB's went fast enough to ever need much more than dragging a boot on the ground outside the door.