I've been hunting these articulated cargo trams or rather, "CarGoTrams" for 8 years, ever since I first spotted on my first visit to Dresden. While they may not be unique in the world, they're certainly very unusual, especially in that they transport exclusively car parts.

en.wikipedia.org/wiki/CarGoTram

en.wikipedia.org/wiki/Tram#Cargo_trams

Officially, DVB, the Dresden transit authority, operate these trams, even if they serve only VW and have VW logos on them.