Answer:
Depends on the contract you've signed when renting a car, you will be asked details to where you're taking the car, or are you going to take it out of state. You will be asked to sign a contract, if you're going to take it out of state and you didn't inform them. maybe you'll fine you or something. it's also against the law because you've signed a contract.
http://www.tradingpost.com.au/Real-Estate/Browse?intref=nav110