Road trip thru Slovenia/Croatia feasible?

I have visited Croatia four times using public transport, but the next time we will definitely rent a car--and in mid-late May you will not have major traffic to worry about. I say go for it! With three weeks, I'd try to stay in one place for at least four nights or more at some point (but maybe I tire of moving more than most).
Croatia is skinny in the south, but you could mix it up by by taking the mainland route one way and through the islands the other. I would probably not pick all four islands--while they all have unique features, you are correct there is a basic similarity, and that many hotel changes/ferry rides are not necessary. Jadrolinija is the main car ferry service if you need to check routes/schedules.

Hi,

A few years back (4, I think), my husband and myself had a self-driving road trip from Croatia to Slovenia. Some friends joined us for part of that time. We had round trip airfare to from Zagreb. We then took a small plane to Dubrovnik to start our trip. After a few days in Dubrovnik with no car, we picked one up (with prior reservation) in town, drove to Mostar and later actually took the car on the car ferry to Hvar. This was great because there were lots of different places we went on Hvar. Then took a car ferry back to Split. Toured around Croatia with no problems at all. Traffic is not bad, roads are good, and GPS/cell phone navigation makes it super easy. You really need a car to get out to Plitvice Lakes (which I HIGHLY recommend). From there we also saw Zadar, Opatije, Pula, Rovinj, Motovun, Hum, many other hilltowns. After that we went on to Slovenia. Was interesting that we could not cross at one place as it was a "locals only" border crossing but this was not difficult, just some retracing of our prior route. Drove to Ljubljana for a few days, Lake Bled for a few days, did the RS Vrsic Pass drive and ended up taking a "car train" which was cool. Ultimately drove back to Zagreb, returned the car and flew home. We had just about 3 weeks. We still remember this as one of our best trips ever!! Please feel free to private message me if I can be of any help.

Kaye

Thanks, valadelphia and Kaye! So far, I'm very encouraged!

I agree with you valadelphia -- we will have some 3 and 4 night stays during the trip. I'm thinking we'll come closer to taking 4 weeks to not be rushed. And, Kaye, I will contact you for some specifics once I do more homework. I appreciate the invitation to do so. :-)

a month--lucky you!
Another thought about car ferries--to avoid backtracking, you might want to look at Lastovo, since it is on the car ferry route with Korcula. It is very quiet but maybe at that point in the trip you might like some r&r.

mcalico:
In October 2013 we traveled in Croatia & Slovenia by car for 3+ weeks. We made reservations only for Zagreb after our USA flight and in Dobrovnik before our Venice flight. This is normal for us to make sure we are ready for any flight problems (hah!). Rented the car in Zagreb after 4 nights, traveled to Ljubljiana (3 nights). Took mostly back roads to Lake Bled (2 nights). Vintgar Gorge is enchanting. Over the Julian Alps to Soca Valley. Lovely drive with interesting history. Stayed in Kobarid, visting the museum & mausoleum. Stopped near Skocjan Caves and visited them the next day. Thru Piran (lunch & shopping), across border (no problems) to Rovinj (3 nights) with a day trip to Pula. We loved the small, medieval with good seafood Rovinj. Next to Plitvice Lakes (1 night nearby). Not to be missed in spite of crowds! Then down the coast: Zadar, Split, small towns. Stopping when dark and usually finding good restaurant advice from our hosts. Ferry from Drvnek to Hvar Island and a narrow road to Hvar town. 3 nights with some short drives to sites but mostly walking town and fort. Back to ferry & mainland coast road to Dubrovnik. Turned car in - stayed Dubrovnik 4 nights. Parking was a problem only in Split. Roads were good if narrow. Signage was good. Other drivers were agressive but usually skilled and forgiving of goofs. There were times when we had to use the new high speed highways and they were very good. The people were initially reserved but polite - opened up to us when we showed interest in their activities, etc. We checked on car rental in Italy and driving to Slovenia/Croatia - too expensive & insurance restrictions even with round trip. One way rental from Ljubljiana to DBV also expensive. Trains from Italy to Zagreb poor schedule for us. Flying from Venice Marco Polo to Zagreb was better time & $. We hope to return soon to Croatia & Slovenia for a similar trip. If you want to visit Bosnia, etc., maybe you could start in DBV and drive north, returning car in Zagreb. However done, you will enjoy the trip.

Three weeks is a sensible time for a road trip to Croatia and add another week for Slovenia. You need longer if you want to stay on 4 islands. Personally, I think a week is an ideal time to see Istria.

You don’t need a car in Dubrovnik and parking it can be a hassle. Can you fly into Zagreb and hire a car there for a round trip? You need vignettes to drive in Slovenia. Some car hire companies don’t allow you to take their vehicles on ferries, so check. You need 3 nights minimum to see each island (you could easily spend a week exploring each of them) and taking a car on the ferry is possible, but relatively expensive. There aren’t any inter-island car ferries, so you have to go back to the mainland and out again, which is time consuming.

Vis is the outlying island which will take longer to get to, so unless you have 5 weeks, I would drop this and focus on those that are easier to reach. On Hvar, I prefer Stari Grad or Jelsa to Hvar town. Many of the apartments on the islands have a 3 night minimum booking.

I would try to visit Krka National Park if time permits.

Keep in mind that to get to Dubrovnik, you must cross Bosnia-Herzegovina. You will first exit Croatia at a border stop where they will check your passport. You'll drive a short distance and arrive at the Bosnia-Herzegovina checkpoint. After you clear this, you'll drive for 20 miles or so and then have to go through another Bosnia-Herzegovina border crossing, then another Croatian border crossing. Depending on the time of day and how busy they are these can be fast or very slow. Make sure you check in advance what paperwork is required at each border crossing for your rental car, proof of insurance, etc.

Regarding car rental in Croatia, I just had bad experiences on 2 of my 3 car rentals with Sixt Car Rental. They “found” damage and charged $400-$500 each time. There was no real damage and what they “found” was previously there. In the second one, they had to look under the car to find damage. In hundreds of car rentals, I’ve never had this happen, yet it happened twice with Sixt and others told us they had the same experience. I believe Sixt staff is trained to do this as a business strategy. I would suggest using another company.

It sounds like you are seeing many places. Many more than we did. I think you will need 5 weeks to enjoy them all. We flew to Zagreb, rented a car and drove to Ljublyana and Lake Bled, visited Rovinj and Opatia. We loved seeing Rovinj but we were glad we stayed in Opatija. Rovinj is a little too touristy and Opatija reminded us more of Nice, France with lots of high end shopping, hotels and restaurants for the stylish European. I think each island is different. We stayed in Korcula and Brac. Brac was quieter than Korcula and I hear that Hvar is a real party island. I believe Mljet is a quiet nature sanctuary. I don't know anything above Vis. Lake Bled was beautiful. Definitely walk around the lake and visit the chapel on the Island and the castle above. Plitvice Lakes in May will be amazing since all the waterfalls should be at full strength. Its difficult to describe seeing so many different waterfalls in such a concentrated area. Driving in Slovenia and Croatia was easy. Parking on Korcula could be difficult due to lack of space. Make sure that if you take your car to the islands that your hotel has parking. As far as taking different routes down and back, I would stay near the coast at least until you head back then you could cut over to Zagreb and north from there to Ljublyana and then over to Trieste. I don't know if its all the same. I found each place to be unique but similar. For example, I thought the feel of Rovinj and Trogir were similar but their stories were different. Split and Zagreb were both very big cities. Dubrovnik was unique but overrun with tourists. We went to the caves at Postojna instead of Skocjan. It was cool taking a tram a few miles underground but personally I hate caves.

Beware of Sixt Car Rental. In 2 of our 3 rentals with them in Croatia, they "found damages" each time and took our deposit. The last time they had to look under the car to "find damage". There was no damage. In both cases, they told us not to worry that our credit card insurance would pay for it. Since I have never had this happen in hundreds of rentals, I can only conclude that this is a business strategy for Sixt Croatia.

WARNING!
Avoid SIXT in Croatia, their policy is to steal your money. This has been going on for years and authorities have done nothing about this very serious problem.

1) Could it be feasible (and enjoyable!) to take a round trip road trip thru Slovenia/Croatia

Yes, definitely! I've driven 2 road trips in Croatia, and Croatia+Slovenia+Trieste. On one trip I flew into Dubrovnik, rented a car and drove up the coast and eventually dropped off the car and flew out of Zagreb. On the 2nd road trip, I flew round trip to Zagreb, renting and dropping the car there.

I'll give you an idea of the 2 combined itineraries (not exactly how I drove them, since they were 2 trips) which could make for a very interesting 3+ week itinerary, easily adding in your cities/islands. You can adjust to fly into/out of Milan, Zagreb, Ljubljana, or (to limit some driving) fly into Dubrovnik then fly out of Zagreb or Ljubljana.

Fly into Zagreb - spend time driving "inland"
Drive to Plitvice
Drive down through KRKA (though if I was choosing only one, it would be Plitvice)
Continue south to Dubrovnik and vicinity

Drive back up the coast, Split, Zadar, islands, etc
Continue north to Opatija
Hook west to Istria / Rovinj, Pula, Porec, Motovun, etc.
(return Croatian car / get Slovenian car?)
North to Piran, perhaps Trieste (especially if you're flying to/from Milan)
Slovenia - head to Skocjan caves, Bled
Fly out of Ljubljana OR, drive back to Zagreb and return car

The driving in both Croatia and Slovenia are easy easy. Google (offline) maps work great!! If you rent the car in Croatia, either ask your rental company if they can provide the Slovenian highway "vignette" or buy one yourself as you cross the border into Slovenia.

I rented a car in Zagreb drove to Slovenia and back. I bought a Vignette at the gas station right before crossing the border to Slovenia. If I remember right, it was cheap but I was slightly confused on how to apply the sticker. Luckily the gas station attendant was kind enough to show me how to do it. Driving in Croatia and Slovenia was easy. The only issue was the traffic around Zagreb on the weekend was pretty heavy.