There was a poster from the RTA up at my vets around 8 months ago saying that in NSW dogs need to be tethered when inside the car. The fine is equivalent to that of not wearing a seat belt. It was also on the news, I remember as when I went to buy seat belt attachments the two local stores had sold out as there was such a rush from dog owners wanting to restrain their dogs.
Weird that nothing can be found about it....