Avis First really exists, but how well it works depends on which car class you reserve, and also you need to know if you're reserving at a Select & Go locaiton or not because the strategy may need to be different.

Avis First works fine for reserving an economy and being bumped up to a compact almost always, or for reserving a compact and usually getting bumped up to an intermeidiary. But I bet it works a lot worse for reserving full size, because what's above that? They probably think "even fuller size", which is SUV!

(OTOH, I've gotten some useless SUV upgrades, even before I became First ie when I was just Preferred, from even Economy! )

However, as documented in this thread:

http://www.flyertalk.com/forum/avis/...o-service.html

the strategy at Select & Go locations may be different. You get the same Exchange area whether you reserve a Full Size or an Economy car, so why not save money and reserve Economy and then you won't feel so underwhelmed by the Exchange area. Plus, then if you want to use the Upgrade area, it's an added cost relative to a much lower initial rate.

(Of course, if your employer is paying for the rental, but won't pay for the Upgrade area, I can't help you there. Select & Go works best when you're paying for the rental yourself, as then it allows you to reserve the lowest class and yet still have a choice of several classes above that for free Exchange or use the savings on the rate to "fund" the Upgrade.)