Some family members are visiting MLB in central FL. It does sound like, at least in FL, Hertz is indeed getting new cars.
I heard MLB had about two dozen cars in the Hertz lot. Most had no front license plate, meaning they were likely new FL cars. There were a handful with front plates, meaning out of state inbound one-ways. Of those, it was mostly the new orange NY ones. So they were probably leftovers from last fall's FL drivein.