No idea what they do, but they give an Elite up to a fullsize car with minimum 24 hours notice. Chances are when they say "sold out" it doesn't mean there was one car left and it just got booked. They probably have a minimum "float" and then block off online so they don't get a ton of bookings at once. Oh and even if you booked fullsize last minute, chances are they'll just give you whatever they have.