For the airports I normally use, I've noticed that the National Car discount (INFINITE) offered by the Sapphire Reserve card often is only good for a few bucks off of the publicly available rate, sometimes $5 or less. I've found the Amex Platinum discount is a much better deal. Has anyone else noticed the same thing?

I like the primary rental car insurance benefit offered by the card, but not if that means paying much higher car rental rates.