Join Date: May 2012
Location: SF Bay Area, CA
Programs: Amtrak Select Executive, Hertz PC, National EE, IC Diamond Ambassador, ALL Gold, Hyatt Disc
Posts: 531
The OP did ask if upgrades are only valid for A-F reservations so that is still answering the OP's question about what the polices are...
And yes... it has been much been answered in various ways. I just hope Hertz does the right thing in the end...