It's been well-established for a long time on AutoPuzzles that Eastern Europe refers to what in English was always called Eastern Europe, which was the old Comecon bloc: Poland, Czechosovakia, Hungary, Romania, Bulgaria, Lithuania, Latvia, Estonia, any Soviet Republic in Europe and East Germany (GDR) - I hope I haven't forgotten any!. Western Europe has always meant the remaining free countries: all the Scandinavian countries (incl Finland), West Germany, Benelux, Austria, Switzerland, France, Italy, Spain, Portugal, Greece, the UK and Ireland. Those are the countries recognised by the question 'Eastern Europe' or 'Western Europe': it's not a geographical question because some parts of Western Europe are further east than Eastern Europe! Although everything changed after 1989 the Eastern and Western European countries are still the same, since this is largely a historical site so it's where the car emanated from, although it gets a bit more difficult now there is only one Germany, not two.. Yugoslavia would have counted as Eastern Europe too, for the same reasons as above.
Hope that's all clear!