There are two rows of National cars parked (close to 50 spaces in total) on the 1st floor of the parking deck. I suspect they consider the first 10-15 spaces to be their Emerald Aisle. IIRC, spaces #1 and #2 say "VIP Reserved" on the signs; and that's where I saw the 2010 Taurus parked. The car I get has always been in one of the spaces 3-10.

I think it's been the same lady in the booth outside each time, and she seems to prefer controlling who gets each car a little more than the big airports. She'll look at the keys for a car in the EXACT class reserved for you. I got the Edge (fully loaded: leather, giant moonroof, etc.) because I was making a one-way rental and someone had one-way'ed it to HSV (seems like playing "hot potato"). I got an Impala because there were no ICARs available.