I am not certain why Marriott, or any other company for that matter, offers promotions with Hertz. As I have often found, such promotions result in much higher rental rates, the latest offering of 5,000 Marriott points for a rental of five days or more and a savings of 35% or more on base Hertz rates, glitters upon first reading but is simply one more Hertz program made of lead, not gold. I recently reserved a Hertz vehicle for a five day rental - the total $511. By applying the CDP# and PC# in the Marriott Rewards mailing to the rental, the price jumped to $740. That's a lot for 5,000 points!
The base rate on the car is $850 so a 35% discount brings it to $552. I'm still trying to figure out the math of how this relates to a 35% discount. Don't misunderstand me; I'm a Hertz President's Club member so I rent a lot of cars but i also use available discounts which actually result in real savings. This one, like most, simply is not gold.