Hertz has mustangs. National has Sebrings. I don't know about the other companies.

We used both a mid size and convertible for our recent trip. I think it depends on what you are doing. If you will be doing alot of driving vs. tours or hanging at the beach, then use the convertible.

Also, reserve it anyway and keep the economy car on hold too until you can figure it out. Check sites, prices can differ greatly. Use a Costco or Entertainment card coupon which might help. I find Hertz so much more expensive.