We plan to rent a car in Split and head east going into Istria area for a few days . Then we will either drop the car in Rijeka and take the train up to Ljubljana or keep the car and drive up and around the area surrounding Ljubljana (Lake Bled, Julian Alps, etc).
Any advice on car rental companies?
Anyone know how the extra cost of crossing the border and dropping the car in Slovenia?
Any tips/advice?
Dropping the car across the border would incur a cost from $250-475 depending on the company you use. These are the prices from the well recommended AutoEurope.com. I'd suggest going to their website to check on pricing and perhaps speaking with one of their service reps regarding your options. I had a Madrid to Lisbon rental a few years ago and the agent with whom I spoke on their toll free number found a deal saving me $150+ on the one way drop fee - which was stlll over $300.
With that drop off fee, I would drive into Slovenia, but drive my car back into Zagreb to drop the car in Croatia.
That's what we did last year. At the time, when we crossed into Slovenia, we had to purchase a vignette at the first gas station to drive in Slovenia.
This past June, I rented a VW in Slovenia; at the time of rental, they asked if the car would be leaving the country as there are extra charges for insurance when leaving the Schengen zone. Since I was just driving in Slovenia, they noted it on the rental form. In all cases, do have the international Driving Permit with you.
Consider the small Croatian company Novarentacar based in Trogir. Friendly folk who answer their emails in perfect English, have cars in all the major cities, and seem more personable and desire to please, so you will return. What a concept.
I think you are confused about geography. Split is far southeast of Istria. Did you mean Split? Are you flying into Split maybe?
My Slovenian houseguests would love you to see their country, but my Croatian wife recommends you stay in Croatia and avoid the expense and hassle of crossing the major Schengen border twice. They have introduced stiffer controls and it can take awhile.
If you are starting in Zagreb, rent the car in Zagreb, do Split to the south, come back north and do Istria, the Croatian side. Leave the car in Croatia and visit Slovenia by bus or train from Zagreb.
Driving in Rijeka is no fun, btw.