Social signalling is relative to the things available for that society. Even if there were no "nice cars" available by your standards, there still were "impressive" cars, relative to the society in question.

I used to live there. East Germans got West German TV. They knew about West German cars.

(And in any case, the range of cars available was much more compressed. Thus there was less differentiation at the high range.)

No I think except for the politicians and military most people just got the standard model of Trabant or nothing.

You could also get a Wartburg, a Moskvitch or a Lada, and a few others. Probably also Skoda, but I don't remember hearing about them back then.

The big brass were driving Volvos. They were nice cars, but Sweden was seen as sufficiently neutral and socialist-like.