If you get a BMW or Audi, couldn't you get it fixed in Germany if anything went wrong?
Might be a problem if the car actually has a driving related issue, mechanics are mechanics be they German, Polish or what ever. Besides the cost of driving to Germany might well be around 5 times more expensive than the fix fee. Thats a really silly idea.
i think to get a decent BM, Audi or Merc in Poland you need to be able to spend over 25,000 PLN.
Most common competitive cars these days are built well. i always check out the star rating on Autotrader and read the owners comments, some really handy info there.
I hate Mondeos and Vectras, maybe go with the Octavia, seems the best of the lot form what you listed.
Holy crap 67 miles to the gallon and a owner rating of 4.75 / 5. thats damn good.
Octavia 1.9 TDI