Renting a car is pretty expensive, especially if you want a decent car -- A/C and automatic. Something like a Toyota Corolla is considered high-end luxury and could cost as much as 300R (with additional insurance). I wanted to explore some of the beaches out around Recrieo and beyond, and didn't want to incurr a 100R+ taxi fares in doing so.

Having an International Driver's License is not required. At least renting a car, not sure what happens if you get pulled over by police.

As far as discount codes, I tried all the one I had with Hertz and Avis and none of them seemed to work. Then I came across one Avis discount code by NetJets (#K444404). It doesn't give a 50% discount, but it is like a good 35% off!
You don't need to show a membership card or any proof.

You can try haggling with some of the other car rental places along Princess Isabel. You might get a lower rate.

Brasil doesn't honor Internal Driver's licenses, you need the special one that Brasil and I think one or two other South American countries have chosen to require.

Brasil just loves to make things difficult for people who want to spend money in their country

Actually Brasil does now honor the International drivers licencse. Depending on who you rent from they will want you to have it. Rented from Localiza and was never asked for it. Rented from Avis and they wanted me to have it and I had to sign a waiver saying I understood that it was necessary and would be totally responsible for any problems.

Wow, an actual change to make life easier, that's a change for Brasil. Now if they can work on getting some muggers and dirtbags and favela rats off the streets....

Hmm, I never been able to get an international drivers license, what you mean is really the International Drivers Permit. They are easy to get as long as you have a valid drivers license in your home country and good for a year.

The are two versions, and unfortunately Brazil uses the old one which is only valid for Brazil, Burundi, Iraq, Nigeria & Somalia. All other countries use a later version. They look very much the same though. You'll need passport photos to attach to it and can get it through AAA.

It's been required in Brazil and internationally for a long time, the car hire companies are often lax about requiring it which is why its not been ask for.

And remember, you are required to carry a valid drivers license from your country as well as the permit in case you are stopped. The police could demand to see both.