It's complicated because I start with AutoSlash and AutoSlash generally gives me the best price via Priceline. For trip #1, Priceline took me to Green Motion Podgorica airport and I dropped at the Belgrade airport. For trip #2, same rental process, but instead of Green Motion, I got the best price from Hertz, picking up at the Sarajevo airport and dropping off at the Ljubljana airport.

A couple of points. At Belgrade, there was a very small return lot, and it was full and the agent was no where to be immediately found. An agent from another rental company tracked him down. The agent, once found, apologized, and said he wasn't expecting any returns that day and he preferred that I return the car when I said I was going to return the car. I had to fib and tell him my flight changed. (The actual reason is not important for here.) At Ljubljana, Hertz was closed on Sundays, when I returned the car. There was a key drop with a sign with the office's e-mail address. Obviously just parking the car, can make one nervous. I took good pics - and don't forget the roof, windshield, and spare tire - just in case. I e-mailed the office Monday morning and they immediately confirmed that all was good.

Finally, a new trip (late 2023). I wanted to drive through Greece, Bulgaria, Kosovo via North Macedonia (missed on trip #1), and return to Bulgaria. The EU rules are complicated and I may be oversimplfying, but no rental car was leaving Greece (EU). So I flew ATH SOF and then rented a car, Green Motion again, and was clear what I wanted to do. I had to pay an additional insurance fee for leaving the country; not a big deal. I left SOF and headed to the North Macedonia border. I couldn't cross the border because the rental car company inadvertently placed a COPY of the vehicle registration card in the car. So back to Sofia, returned the car, and got my money refunded as it was the agency's mistake.

A few more points. You can have all of the evidence of insurance you want. It is simply not accepted in the Balkans - not sure if there is just not an understanding of it or it is a money grab. If you don't want to pay for insurance, have enough credit to allow a hold for the value of the vehicle. Bottom line, full coverage was just a few additional dollars a day (I think less than $10 for my last trip).

If there were one-way drop off fees, those fees were not memorable. (For trip #2, as I had lots of time, I wanted to drive from Sarajevo to Barcelona and the one-way fee was $2200, no matter the rental company; again something EU-related.)

When planning your trip, remember that if you enter Kosovo via any country other than Serbia, you can't enter Serbia from Kosovo. If you enter Kosovo via Serbia, no problem.

Most importantly, don't fib to save a buck. Be up front about the countries you intend to drive through. The 'green card' (insurance card), as well as the vehicle registration card, is carefully inspected at the borders and if the country you are entering is not listed on the insurance card, you're out of luck.

I enjoyed my road trips very much through the Balkans and I'll return to do more.

(I am not sure about the other poster's comment about Albania. I had absolutely no issues around Tirana or any of the many rural areas I traveled through.)