They will send you a packet in the mail with a card. You will never probably need to actually show the card unless you need the number to make a reservation at the counter, the rest of the time it will be in the system. I've never needed it.

I've returned probably over a hundred hertz cars, and I've never had a private shuttle to the terminal, that was incredibly good luck.

You may get an upgrade from time to time, see the thread on upgrades

http://www.flyertalk.com/forum/hertz...ades-here.html

But don't expect one, if there's a class of car you need, reserve it don't plan on something lower and getting an upgrade. You could also go in and ask if they have something different if you don't like what's parked in your spot.