Thanks for the replies again guys, I only go to Brisbane (son and family live there). Being as we go out there primarily to see them and the grandkids I don't really want to be taking a week out to visit Melbourne etc. but advice much appreciated.
I've got to ask something, why are second hand cars so expensive in Australia?!! When I first went over there I thought about just buying a second hand one and keeping it at my son's house rather than renting each year. I nearly fell through the floor when I saw the prices. Apparently the car I ran at the time which was a two year old VW Passat and cost me about the equivalent of $15k would have been bonkers money over there.