Is it possible to rent a car mid- to late-June in Croatia without advance reservations? I'd like to stay flexible with my schedule, so I'm reluctant to lock in on a car ahead of time. Thanks.
Suggest you try SIXT car rental. We rented from them in early May but only booked the rental "on-line" about a week prior to picking-up the car. We had checked other companies for rates and pick-up/drop-off locations. SIXT offered the best prices (by far) and locations which best fit our itinerary as we were only renting the car for 3 weeks of a 6 week vacation on Croatia, Slovenia & Austria. The big pluses were - we could drop the car off anywhere in Croatia without any additional fees; we could drive it into Slovenia (which we wanted to do & did) without any additional fees; and the service by the company was outstanding.
Prior to booking the car rental, we were advised (by a SIXT agent in Opatija) that reserving the rental on-line was cheaper than directly with a local agent and if wishing to buy additional insurance, buying it from the local agent was the best option. I checked out both options and the Opatija agent was 100% correct.
Hope this helps and that you have a fantastic "being flexible" vacation.