Brač is an island, so a rental car must cross the Adriatic by ferry. For a typical four to five day island-only stay, renting a car directly on Brač is normally cheaper and less stressful than ferrying a Split rental across. Arriving as a foot passenger avoids the round-trip car-ferry fare and the mandatory island surcharge that mainland suppliers add. The Jadrolinija Split–Supetar car ferry (line 631) costs €18.20 one-way in low season and €26.10 in high season for a standard car up to 5 metres, with adult foot fares of €4.40 low and €6.50 high; the crossing takes about 50 minutes and runs up to 14 times a day in summer. There is no vehicle reservation on this route — cars board first-come, first-served, and on July and August weekends drivers may wait 1.5 to 3 hours and be bumped to the next sailing. Mainland brands allow island-ferry travel but charge a fee that, if unpaid, voids all damage protection: Sixt €7.85 per day capped at €54.95, Hertz €5 per day capped at €75, Enterprise €17.50 flat; some local agencies such as Lutar and Avax charge nothing. A car rented on Brač must stay on the island, and a one-way drop-off in Split triggers relocation fees of about €250 to €300. Bringing your own car wins mainly for stays of roughly six days or more, or when the same car is genuinely needed on the mainland. On the island, stay on paved roads: every operator voids cover for damage on macadam or off-road tracks such as the approaches to Blaca Hermitage, though the paved summit road to Vidova Gora, the 778-metre high point of the Adriatic islands, is fine for a normal car.