From my memory of owning cars in Aus nothing that was ever needed desperately was sent by the mail regarding the car. That is, all proof of ownership is online and transfer of ownership is online/mail anyway, no car papers/proof of insurance is needed (insurance isn't compulsory but probably should say its recommended before someone bites my head off). I could be wrong with some of this though...
I used juicy campers when in NZ and they pretty much hit the nail on the head for what needed. Nothing flash but it does the job! Anything more than a couple months rental can be expensive though and you don't have the potential resale value. Flip side though, the car is likely to be reliable (or at least you can tear them a new one if it isn't) which is better than the ~$2000 or so in repairs i've had to spend on my camper van whilst we currently travel Europe. You also are less likely to have your hand forced into buying a car that you don't quite want out of pure lack of choice (sometimes the right car doesn't show up for weeks or its too far away and getting there is a pain in the *** in the mean time you have to pay $30/night or something for a bed in a hostel).
I guess what I'm saying is that there are some serious pros and cons of both sides that only you can weigh up but you probably already knew that. Buying your own car can see yourself come waaaaaay out infront if things go well but it has bigger risks involved whilst the rental car is super simple but bloody pricey. Personally, i have chosen to buy cars in USA and currently in Europe as we figure even if we sunk a bit in for repairs and then wrote the car off it would typically come to the cost of a rental on an extend trip.
