I was wondering if there was a BBB equivalent in AUS as we have in the US.

Here's what I found so far:

http://www.fairtrading.nsw.gov.au/default.html
http://www.accc.gov.au/content/index....htm#consumers

I am basically looking to rent a car in downtown Sydney and looking to see if there have been any issues with Europcar, Alamo, Budget, Avis, Hertz in downtown Sydney. The price quoted by Europcar and Alamo are much lesser than Avis/Hertz. What am I compromising on? What would you guys suggest?