T4 Terminal Car Park: built for Terminal 4
If your flight leaves from Terminal 4, this is the closest thing to a dedicated option. Melbourne Airport says the T4 car park is about 100 metres from the terminal, which is a short outdoor walk rather than a shuttle ride. That distance is the whole point of the product.
It suits the airlines that use T4 and the travellers who book them: short domestic hops, carry-on only, no interest in waiting for a bus at 5am. If you're flying out of T4 and back into a different terminal, check your arrival arrangements before assuming the same walk applies in reverse.
Because the whole walk is outdoors, weather matters more here than at the multi-storey options. Factor in a coat if you are travelling through a Melbourne winter and plan on a covered stop at the terminal entrance.