Renting a car to cross multiple countries in Europe?

[Pulse]

Ideally want to start in Austria, but totally flexible. We’d like to hit a few countries across 5 days. Thinking currently...

Austria, Slovenia, Croatia, Bosnia, and back up. Could easily skip Austria, the others less so because I haven’t been to them.

But as I say, totally flexible. Would love people’s experiences of doing similar. We were going to take a UK car but since neither of us own a car right now, and one of us is short on time, it doesn’t seem worth it.

Thoughts / recommendations would be really appreciated.

[Pulse]

Thanks everyone. It's becoming clearer, but I'm still not 100%. The countries we'll hit are now confirmed - Austria (arrival and departure), Slovenia, Croatia, Bosnia & Herzegovina... with Montenegro and Hungary as possibles, but not likely.

In the exclusions lists for both Sixt and Europcar (the two main suppliers in Salzburg airport), whilst they say there are restrictions, I'm not clear on:

1. If we cross the border, how do we pay for vignettes / tolls?
2. If we cross the border, what are the fees?
3. How do we ensure (since they all say 'or equivalent') we get a certain manufacturer (since some are not allowed)?

Anyone with experience of this?