Originally Posted by AutoSlash

We don't really see the Amex Plat code come up very often as the best discount. Sometimes, yes, but far more often it's others (AAA, USAA if you can get it, and, heck, even the UA MP member one). Anecdotal, yes (I didn't dig in the data to verify), but that's my impression based on the literally millions of rate queries we've performed. You're welcome to use the quote/track links in our signature below to see if there are other codes that are as good or better for your upcoming rentals.

Do you have to physically hand in your Platinum card or can you keep it and claim you misplaced it? If so, carry it around with you and in the very, very unlikely event they ask you for proof of eligibility to use the code, you can show it (you don't actually need to put the rental charges on it, of course).