TXT reply from my MB tech buddy:
"Benz does indeed lock out incoming and outgoing data and it can only be read using a proprietary SDS. Benz loves to keep people coming back for their expensive service. You even so much as pop a hood latch once, and you pretty much voided any warranty on the car."
For the record, he doesn't drive a Merc and neither do the other techs there. Imagine that, heh.