My newest purchased train set is this BASF advertising train
They were distributed or sold to radio and television dealers in the late 80s to early 90s
The transformer that is included is marked 14. 06.1989
There are 12 curved tracks and 6 straight tracks included.
It could then drive around with different of their cassette tapes or reel tapes on the 2 flatbed cars in an exhibition.
I have previously bought a couple of wagons with the BASF logo here in Denmark
I don't know if it is only in this country that they were distributed/sold.
more pictures here
https://photos.app.goo.gl/oVQyQtvHa5vaAQf77