I am flying into Sofia and out of Bucharest, and exploring options on crossing the border. I'll spend most of my trip in Bulgaria and the last few days in Romania. I'm renting a car in Sofia. My plan was to travel roughly east and see a few Black Sea beaches, and then cross into Romania. My options seem limited and involve quite a bit of compromise.
I cannot find good options to return the car anywhere close to the border and cross over. I do not want to rent from a local rental company because of the stories I hear of hidden fees and bad experiences, so I'm limited to large international companies.
I can return the car to Sofia and take train/bus/plane to Bucharest (major loss of total travel time)
Drop off the car in Varna (very expensive) and fly to Bucharest
Getting from Bulgaria to Romania must be common, so what are the other options?
Thank you.