Melbourne to Port Augusta is a romp with the Superchargers, Port Augusta to Perth is slow but comfortable with correct planning and patience. Not many drivers cross the Nullarbor to save time or money, it's the adventure more than anything.
Port Augusta to Perth can be done in 4 days with 3 overnight stops, daylight driving only, better to add two extra days and go via Port Lincoln and Esperance for a bit more scenery. Grab a juice booster, spare tyre and a some reading to catch up on, then be the first model 3 to cross the continent.