Great find!!!
These are B27E! Definitively!
The B28 came late'80/1981 with the "new" front.
It's a Bertone assembling as well:
here you can read a bit over the TE's history:
http://www.volvobertone.com/
Here we have a car - rental service, where you can rent one for marriage (driving to church etc.) or company events / exhibitions...
It's a kind of "eastern - Germany - nostalgy" (Erich Honecker's car...)