You should be able to but you'll pay for it! I.'ve hired cars in the states at 22 or something.
Great holiday- Miami, Keys, Naples and Orlando.
Just do what I do and say 'check what's she's wearing, you wouldn't get away with that at home!' Then say things like 'she shouldn't be wearing that at this time of night' or 'is she famous? I'm sure I saw her in your copy of hello!'
Never fails!