Originally Posted by philemer

As long as some amount is charged on your card you're good to go.

Originally Posted by storewanderer

Should not matter, you will still have taxes/fees charged to your Chase Card on the rental. This shows on the National Receipt and Contract like a coupon.

I have not had a Chase claim for car rental damage when using a National Emerald Club Free Day but I have had Chase claims for car rental damage when using, for instance, $20 off weekend car rental, or "rent 2 weekend days get the 3rd day free" coupons without issue and without question from card benefit services.