Date registered: Jul 2005
Vehicle: 90 300E, 99 ML430, 00 ML320, 05 E500 4matic Wagon
Mentioned: 18 Post(s)
Quoted: 877 Post(s)
They never came with the car from the factory.
The slots allow for hot gas to escape and help to clean the pads under extreme duty(GT class racing). For regular driving they are not going to make any difference.
You can save some money and get the regular rotors your car calls for. I really like the Zimmermann rotors for the W211 cars.