You have until 12/15 to go to
www.opensavings.com/hertz and make a booking in order to do so you will have to join Hertz Gold (free 1st yr with the Amex SPG BIZ CC)
you can use any codes that you find that will lower the rate just be looged in and use the URL above
my 1/7 4 day rental will now be appx $25
bear in mind you will still get the reg 5% disc you get for renting and using the Amex SPG Biz CC
also the Rental need not be started or completed by 12/15 Only booked by then as per the CSR at Amex SPG Biz