I think you are looking for elite levels within the Perfect Drive loyalty program, right? AFAIK, they don't exist...you just get upgrades tossed your way more often if people notice that you are a frequent renter.
I think Hertz is the only one that has formal Elite Levels, although something tells me Avis has something similar (I don't rent from Avis, so I don't know firsthand). I'm a President's Circle member at Hertz, which usually translates into a 1-car-class upgrade at most airports. The membership materials say it's "guaranteed upgrades", but in practice many Hertz employees don't even know what the levels mean, so the upgrade isn't always there.
But...if you rent a lot at large airports and you want a high upgrade percentage, you might think about Hertz... Their points program is pretty boring - no merchandise - but you earn free rental days at a decent rate, so you aren't losing much unless your main reason for choosing Budget was to hook up a new set of Callaway sticks.
[This message has been edited by rmccamy (edited 07-08-2002).]