Davos said:
I would recomend hiring with Hertz paying the extra $10usd per day and getting a car with the Never Lost system, makes navigating you way around a snap, the last thing you need when driving on the right hand side is worrying about trying to read a map. The only thing is they tend to only fit the systems to the meduim (Commodore,Falcon) sized cars, and above. Also not available in the soft top Mustang (Damn it i really wanted to hire one last trip) I guess due to the theft factor..
I also recommend the Hertz Neverlost of you are travelling alone and don't have anyone else to navigate. Its well worth the extra cost! Its normally available with the Ford Torus, which is what they call a Full Size rental.
Check your insurance options when you make the reservation on the net so you are not under pressure to make an on-the-spot decision at the pick-up desk. Know what your travel insurance covers and what you expect the rental car agreement to cover.
Stick with the major rental companies such as Hertz, Avis, Budget as they tend to be reliable and ethical.
An International Drivers permit is not essential. You can rent a car and drive in the USA with an Australian Drivers Licence. However, I did once have a run-in with a Maryland Law Enforcement Officer who (incorrectly) told me I did need an International Drivers Permit unless using a US, Canadian or Mexican drivers licence. So I now carry one whenever I drive in the USA just to be sure I don't have another threat to throw me in the slammer. They are available from your local motoring association such as RACV. You must carry your Australian drivers licence on you at times while driving, and its a good idea to have your passport handy too. In my Maryland episode, having my Aus DL, passport and airline ticket available to prove I was not an illegal immigrant allowed me to drive away with a "I will let you off this time, but next time I will impound the car and you get downgraded accommodation for the night" warning from the ill-informed cop.
As with any rental, check the car for damage before leaving the rental car lot. And don't leave your valuables locked in the car in a public car park as such theft is not covered by most insurances.