I talked to an old time Mercedes parts manager about premium pads. His comments to me were roughly as follows. Mercedes brakes are way overdesigned, and that the regular organic pads are very adequate for safe stoping in a family car. The only time the premium pads(metalic or ceramic) were going to buy you anything is if you were racing and continually braking at high speeds. If you were regularly driving in the mountains and on long steep downgrades with a load of kids that might count too. Under these circumstances the premium pads will take the heat with out fading. Further, as already has been mentioned some of the premium pads screach and are anoying in stop and go traffic, and wear out expensive rotors much faster.

Changing break pads is a relatively simple job, really not too much more difficult than changing oil or fuel filters. I'll bet I could change 5 or 6 sets of pads in the time it would take me to change the rotors. I usually opt for premium parts, but in this case I go for the cheapies.

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Sedecrem

82 300SD 290k(needs engine swap)
79 240D 354k with new heart transplant w/220k
82 240D w/auto tranny soon to be manual 4 speed