Hi - depending on where you are staying (i.e., do they charge for parking?) and how much touring of the island you plan to do ... you may find you only need a car for about half that amount of time. Just compare the rates of the major rental companies on-site at the HNL airport. There are smaller, private rental companies on the Hawaiian Islands that ARE cheaper, but I personally stick with the well-known companies (Hertz, Avis, Budget, Dollar, ...). If you Google "rent a car in Honolulu" you will find the sites to these other vendors. Hope this helps!