We want to take the ttain from Florence to Trieste and spend the night in Trieste, then pick up a rental car at the airport and driving into Slovenia, Croatia, Bosnia and Montenregro and then dropping off the car at the Dubrovnik airport. Do some car companies allow you to pick up a car in Italy and drop it off in Croatia? How much is the drop off fee? Can we drive into Bosnia and Montenegro? Thanks!
You can drive anywhere in the area. Regarding the option of renting in Triaste and dropping in Dubrovnik, that could be an expensive option because of the country to country drop off fee. You could also travel to Trieste by train, take a bus from Trieste to Rijeka (2hours and 15min) and rent a car in Rijeka, which is in cCroatia. That way you would save the drop off fee. bus stops near the Trieste station. Bus company website below: