Croatia and Slovenia Sept/Oct 2022

"Any extra costs we should be aware of"

You'll need a a Vignette for your car in Slovenia : https://evinjeta.dars.si/selfcare/en

"explore Slovenia for a week"

Have a look here for a place to stay for part of your week in Slovenia - https://tk-skerlj.si/en

I read about this place in the NY Times - https://www.nytimes.com/2009/07/05/travel/05explorer.html and did stay there for 3 nights - family run - literally everthing that you consume at breakfast or dinner is raised or grown on their farm - beautiful courtyard to enjoy your meals. I totally enjoyed my stay there.

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I always enjoy the drive to Lake Bohinj, taking the Vogel Cable Car up to an expansive day of hiking and the views across the valley of Triglav.

We rented a car in Ljubljana and drove into and out of Croatia and returned it in Ljubljana. So I don't think issue taking over the borders. But the drop off fee for a one way rental in a different country can be expensive. You might consider using the bus back and forth between Croatia and Slovenia and have two separate car rentals, one in Slovenia and one in Croatia. We used Flix bus which were very nice buses and very inexpensive.

In Ljubljuana we rented from one of the major companies, not remembering which one. But reserved through AutoEurope. The location was in one of the hotels in the center of town but it was still easy to get out of and back into using google maps.

@ Laurie Ann - I think the OP is renting in Croatia and returning to Croatia.

Just make sure your rental company knows you want to take it across the boarder. There is usually an extra fee and they give you a type of passport for the car

It was my suggestion to OP to consider if bus to Ljubljana and rent car there might be easier and less expensive.

Driving from Croatia into Slovenia coming and going? Border/travel Issues?

No. Just normal leaving one country and entering another. Depending on various factors, including which crossing you use, it could take no time at all or it could take an hour or two.

For the car, be sure you have told the car rental company. They will give you appropriate paperwork to have on hand. As someone mentioned, you will need to buy the vignette for Slovenia before you leave Croatia. Gas stations just before the border should sell them.

Any extra costs we should be aware of?

1. Cost of the vignette and 2. the cost for dropping in a different location than you rent from (this one will be included in the cost of the rental itself).

Best companies to rent from and easiest to pick up and return?

I have only rented once so I can’t say “best”. But I used UniRent and was very happy. They have both airport and downtown rental available in Zagreb. Same for Split upon the return. I rented in Dubrovnik and drove for 5 days in Slovenia (in addition to the places I went in Croatia) - and returned the car to the downtown location in Split.

Flying out of Dubrovnik.

Use the ferries Split to Dubrovnik. You might decide on some island stays. They are gorgeous.

Thanks to all you savvy travelers. Great advice and more fun ways to explore.