Yes, it is often possible to extend the duration of a rental agreement with Avis. Customers frequently have the option to do this online, via the mobile app, or by contacting a local Avis location. The extension is subject to availability and may incur additional charges, which can vary based on the vehicle type and length of the extension. It is important to address the extension before the original rental period expires to avoid penalties or complications. While there may be various terms and conditions attached to the extension, specific details regarding pricing and availability can change. Therefore, it is advisable to check the current Avis website for the most accurate information regarding the rental agreement extension process.