A Car is a Car
Getting a good deal on a rental car is simple. Search all the rental car companies online, and choose the cheapest one that fits your needs. They carry different brands of cars, but besides that, you pay for the gas, and there is no charge for mileage, so it's pretty much what you see is what you get.
Economy, Subcompact, Convertibles & Minivans
We recommend that you rent the smallest possible car that suits your needs. Fuel is expensive here so you will save money with a smaller, more fuel-efficient car.
Parking is easier as well.
There are two problems with convertibles. First, they are over-priced. Second, you will likely be getting plenty of sun during the day - the last thing you'll want is to be in the sun when you are stuck in traffic.
Minivans cost 5 times more than subcompact cars. If you think you need a minivan for your family, consider renting two smaller cars instead. In the end, this may save you money.
Your Auto Insurance Policy in Hawaii
Double check with your auto insurance provider to make sure your insurance policy is transferrable to Hawaii. With some policies, you may not be covered in Hawaii, so double-check this with your insurance agent.
You don't want to be left holding the bill if something happens to the rental car while it's in your possession (door dings and dents, vandalism, etc.)