Yes, it is typically possible to modify a rental reservation online with Dollar Rent A Car. Customers can often access their reservation through the Dollar website. By entering their confirmation number and last name, they should be able to view their booking details. Once logged in, they can make various changes to their reservation, such as altering the pickup or drop-off dates, updating vehicle choices, or modifying personal information. However, it is important to note that certain modifications might be subject to availability or may incur additional fees. For detailed guidance on the modification process, it is advisable to explore the rental policies listed on the Dollar Rent A Car website or the dedicated reservation section where more information is provided. If specific questions arise during this process, the current web page might have the relevant contact information to assist further.