Basically, the way that these work (in my personal experience) is that you can use any Hertz CDP code (I routinely use my corp code or 212, which is AAA MidAtlantic) to get your base rate discount. This isn't considered "any other voucher, coupon, certificate, or promotion" by Hertz.

The dollar off certs is given to you via a PC code. The PC codes are usually stackable upto 3 certs as long as they have the same PC code. So, if the PC codes is 123456 on all 3 certs, you put int 123456X03 (where you use X0# where the # is the number of certs you have upto 3).

So, you should be able to use your normal CDP discount & get upto $150 off your car rental. The only thing, IMHO, that is YMMV, is whether or not you'll get your credit - and like I said, I've always gotten rental credit & ZE1 points or Virgin Atlantic Miles credited to my account with no problem.

Also, for what it's worth - that T/C language isn't Marriott's T/C language - it's Hertz's - and as for being intelligent enough to see through it, it's standard contract language for Hertz.