I'm not sure there is a process, I'd say upgrades are more result of availability. With that said, I have seen a pattern develop with Hertz recently that seems positive as it relates to upgrades. I have been PC for the last several years. I used to book a midsize through my corp TA and usually ended up driving a Taurus. With the advent of Neverlost--I would book a midsize w/neverlost through my corp TA and end up with Taurus, Subaru, Explorer, Excursion w/Neverlost. In the last several months I have been booking the majority of my cars online. I book midsize w/neverlost and now I have been getting--Explorer's, Volvos's, G-35's, Town Cars, etc. I don't know if there is a greater power at work, but my midsize/neverlost reservations online seem to be working (knocking on wood)