My only clues are that I rented at least 70 days from Avis last year, or that I just made Platinum on Delta. If it's because of Platinum, I expect upgrades from the other rental companies. (What's above Hertz #1 Gold?) Yesterday I showed up (stupidly) with no reservations. Several people said "no car no way", but when I showed my new card to the guy behind the desk, he went off to talk to the manager (not at my request), and got me a nice minivan.