Ok, the MB is for Mercedes-Benz. The MB-Sachnummer is simply the Mercedes part number.

Sonderausfuehrung ("ue" being the u with an umlaut ((two dots above it))) means literally "special model," or "specially designed model."

I don't think I'd throw the label away, especially with the Mercedes-Benz part number on it (that's pretty cool, I think), but by the same token, I don't think it's crucial.

Maybe just laminate it and throw it in the glove box or keep with it insurance.

Maybe a native speaker will know what the PZ means. I'm on exchange in Germany (not too far from Osnabrueck) and I'll ask around if anyone here knows what the PZ might be.