1 series are good fun, but even a 330d will do the job nicely.
They're not slow... And will return ludicrously good economy on the highway. As a bonus, you're likely to get a manual.
C30's are nice. Diesel especially. Many torks.
Z4 is laaaame in base trim, which is what you'll get.
The C180's are a slug. Even in manual.
As for the DO NOT GO clause... It may be wise to pay attention to it. Czech Republic is *usually* ok, but the Balkans, Ukraine, and Allthestans are out. Which is a shame, 'cos Croatia is stunning (as are the girls... My god, the girls)
That said, I did get all my windows smashed out in Prague, but I'm told that had more to do with the Munich plates on the 540. Apparently there's some centuries old lingering hostility there.