Like most rental companies, the grace period is 29 minutes. Once you pass that point, you are charged for an extra hour based on the rate displayed in your rental contract. If you return more than 1 hour and 29 minutes late, you are charged for two hours. If you return more than 2 hours and 29 minutes late, you are typically charged for an extra day. All of that said, rentals are priced based on a 24-hour day, so it may depend on what time you picked up the vehicle.