The direct inland drive can be done in a day. The coastal journey deserves nearly a week. Six days gives each region a role rather than treating the whole trip as a race between two capital cities.
A six-day outline
Melbourne to Lorne or Apollo Bay
Meet the Surf Coast, choose a few lookouts and finish early enough for a coastal walk.
Otways to Port Campbell
Balance rainforest with the limestone coast. Do not make the Twelve Apostles your only stop.
Port Campbell to Port Fairy
Spend the morning west of Port Campbell, then slow down for the volcanic western district and Port Fairy’s walkable centre.
Port Fairy to the Limestone Coast
Cross into South Australia and choose a base according to your interests: coast, caves or Coonawarra wine country.
Limestone Coast to the Coorong
Keep this day flexible. Distances are longer and the quieter lagoon landscapes reward daylight.
Coorong to Adelaide
Approach Adelaide without rushing. If the city is part of the holiday, stay at least two nights after returning the car.
One-way logistics
Compare one-way vehicle fees with the value of not backtracking. Confirm whether your hire agreement permits every planned road, and do not assume a standard rental can use unsealed routes.
When six days is not enough
Add a seventh day to the Great Ocean Road or Limestone Coast rather than creating another single-night stop. With fewer than five days, consider the direct inland route or fly and build a smaller loop from one city.