We’ll considering renting a car in Slovenia, driving into Croatia then into Italy. Aware of drop-off fees already. But curious if there are any concerns at the borders or if they are simply a “keep on driving”.
You definitely need to let your rental car agent know that you are crossing over the border to Slovenia. They should let you know of any requirements needed.
That said, here is a recent thread from last year that should answer your questions and then some... https://community.ricksteves.com/travel-forum/croatia/cross-border-rental-car-driving-from-croatia
As all three of these countries are in the Schengen, there is no "official" border any longer. Yes, there might be border police waving cars through which might create a brief slowness, there is typically no need to stop your car. Lots of profiling happening, however, so if you are not white, then you might expect to be stopped.
Notably, in Slovenia your car will likely (but confirm) come with a Vignette allowing use of the highways. In Croatia, there is no vignette, but there are toll booths (they take cash and credit card - you take a ticket as you enter and then pay when you exit the highway). In Italy, there are other systems that can be more complicated with a car, like ZTL.
Emily and Mardee: Thanks so much! Your responses and the thread answer most of our questions. Cheers!
When I rented a car in Switzerland, I was told that driving into Germany was no problem, but that I was not permitted to drive into Czech Republic or Poland. I suggest that you make certain the rental company does not have an rules affecting your trip. I have heard that many rental contracts prohibit taking the car on a ferry, BTW.