The writer / website owner, Graeme Wilson, has been around Australia 5 times in 53 years, and has done over 2 million kilometers since 1972, almost all the time solo. I have managed to travel at very low cost, substantially less than what I see advertised on other websites, and from reading other peoples comments.
I have been to many places that the main stream travellers don't go to or just don't know about, entirely in small 2 wheel drive and front wheel drive cars, and have proved over and over again that you can drive around Australia in a small front wheel drive car.
When I started traveling in 1975, I would sleep in the back of the car. It was a Ford Cortina, TC model, and I don't recommend sleeping across the seats of any car. This kind of prolonged sleeping will damage your knees and back. I suffered from knee pain until 1988 and have ongoing problems with back pain.