Robbo,
This is the topic that I raised about this:
http://bushwalk.com/forum/viewtopic.php?f=3&t=2322&p=23605&hilit=car+hire#p20429We ended up with Budget and I was quite happy with them. Of the major providers they were OK with unsealed roads etc. Most others were not, or had ambiguous clauses in their T&Cs. Didn't have any problems and no unexpected credit card amounts turned up after the trip. I was a bit careful about where I went though, so probably minimised the risks myself to some extent. I remember we attempted to go up one of the dirt roads on the Blue Tier and were stopped by a fallen tree (almost) blocking the road after quite a few kms. We tried to move it but it was too heavy so decided to abandon the idea. I
may have just squeezed past but more likely a few surface scratches would have resulted. In my own 4WD I would have done that but wasn't going to risk it in someone else's. If I can find the name of the guy I dealt with at the Launceston depot I'll PM it to you. I found him to be helpful both on the phone and when we arrived, and he had some bushwalking awareness. Whoever you go with, make sure to do a thorough inspection of the vehicle with the hire representive and ensure that they document all existing damage, including underneath and inside, before you take delivery.