All I know is the first time I came down to Florida I was SHOCKED at what the car rental prices were compared to the Midwest.
I 'assumed' the franchise car rental rates/deals were the same across the states. It most certainly is not true for Florida.
As the rental manager of one told me:
"the rental rates are based on what the market will bear especially if you are within driving distance of the mouse house." :(
So make some phone calls before you decide so that you will have a reasonably priced rental available at your destination.
I bought a toad a week after searching for a rental that didn't cost me an arm and a leg and finding out that doesn't exist in Florida!