Autumn driving notes from the Balkans: the coastal road from Herceg Novi to Kotor stays busy until late September, but after the first week of October you can drive it at any hour without queues. Fuel in Montenegro is noticeably cheaper than in Croatia - worth planning your fill-ups. If you are renting in Dubrovnik and crossing the border, tell the rental company; most charge a small cross-border fee but a few cheaper quotes don't allow it at all.