I'll repost it here from my Holiday Inn Resort Galveston thread
Holiday Inn Resort Galveston Texas USA : Masterthread

At check in, reception will acknowledge that you are diamond elite ....
Asking if you came by car and that you can park on the Diamond elite reserved parking spot.
They fill out a card in some code ...,

And you are asked to put this visible in your car window ...,
I remember that the hotel has a 'kind of in your face - unable to ignore" signpost that exclaims towing according to t&c rules apply..,,



So indeed, a pretty smart invention and benefit of coming by car as a diamond elite