You may have missed it, but a number of national car-rental places amended or ended their car-rental grace periods this year. These were rules that said if you returned your car an hour or two late, they wouldn’t charge you for the overtime.
Dollar, Enterprise, and National have no grace periods. And at Hertz, if you return your car after closing time they’re allowed to keep charging you hourly until they open.
Upgrade: Travel Better has a list of each company and their revised policies. Check it before your next rental. — BEN POPKEN