The announcement about the Car Rental benefit for AMEX personal and business Platinum cards was something that caught my attention.

You need to use the AMEX corporate discount code to get the grace period.

The relevant terms and conditions are here.

Child seats, satellite radio, and liability/loss coverage are not included in the Grace period.

[5] Savings applied to pay later base rate only and vary depending on date, location car class and other factors. Base rate includes time and mileage charges only. Discount does not apply to taxes and fees.​

[6] Guaranteed car-class upgrades on rentals of economy through standard cars with a 24-hour advance reservation.

[7] Upgrade to the next car class at no additional cost when a Mid-Size or larger vehicle is booked at participating locations worldwide. Maximum upgrade is to a Premium car. This excludes Special Equipment such as Minivans, SUVs, Hertz Dream Cars, Hertz Adrenaline Collection, Hertz Green Traveler Collection and Hertz Prestige Collection vehicles.