I've booked Hertz through the IHG link several times. Always a hassle to get what they promise you, but if you're persistent the points will post eventually. This last time was in the Cayman Islands in October, 1 week, not prepaid. After waiting 6 weeks for my points, I contacted IHG, was told to contact Hertz, so I did. After back and forth, they claimed the location was not a corporate owned Hertz location. I said nothing in the T&C's mentions that and the promo code is listed on my reservation and receipt. Took about 3 more weeks of back and forth. I needed the points to post properly as Elite qualifying. Dealt with a very rude IHG manager at the call center, Hertz CS was actually very nice & helpful. Eventually I received the needed elite qualifying points and then some--double posted. So just depends on how much time you want to spend back & forth with IHG's lousy call center & email reps.

Since it says no prepay rates, I would not count on getting anything. Strange there's not an option to pay when you get there.