We are travelling from Split (then to Plitvice) to Trieste via Slovenia in September - this portion of the trip is about a week long.
The options I have worked out are:
Hire a car in Split, drop at Trieste airport. Pro is obviously, this is convenient. The one way fee seems to be around the $800AU mark though which is a little ridiculous!
Hire a car in Split - drop in Zagreb (not in our itinerary as it stands), then get a train to Ljubljana, hire another car there, drop it in Koper (near the Slovenian border) and get a bus from there to Trieste. This option wont have a drop off fee but its more inconvenient and also 2 short car hires will probably be more expensive than a single week hire anyway.
Hire a car in Split, drop in Zagreb, then get a train to Ljubljana and not have a car in Slovenia and rely on day tours or public transport.
In Slovenia, we want to explore some small places near Ljubljana, go to Bled, see Skojcan Caves and go to Lipica Horse Stud. I want to be there for a while and see the performance, go on a carriage ride and tour the stables. There are day trips from Ljubljana that cover the caves and the stud farm, but I'm not sure they'd stay there for the length of time I want to. If that's the compromise we end up making, that's ok, but I'd like to think about all of the options first.
I know there would be lots of people that have done this route and I would love to know how you did it. I feel like I haven't found the right balance between cost and convenience yet. Can anyone help?