How to extend an active rental?

How can I extend my active rental? 

All rentals can be extended up to a total of 28 days with a successful authorization. You can easily extend your active rental via the self-service link below. 

If you need an extension over the length of 28 days, this will require a new reservation and rental agreement. Please book your reservation online to prepare.
 

When is an additional day charged?  

All rentals are charged based on a 24-hour billing period. Only when a rental exceeds a cycle of 24 hours will any additional daily charge apply. For example, if you picked up at noon on day one and returned at noon on day two you are within the 24-hour billing period and will be charged for one day. However, if you return your vehicle at 1:00 PM, you will be charged an additional day.