The present invention concerns an automated vehicle rental system for a fleet of rental vehicles, where the vehicles are geographically distributed and normally locked when not rented. At least one of the vehicles, when not in use, is parked in an unguarded location. The system has a vehicle communications unit for enabling communication to and from the vehicle, user-carried electronic devices, or other readers, and for interfacing with the user. An on-board unit (OBU) is located on each of the vehicles for interfacing with the vehicle communications unit, and with a door unlocking mechanism. The system further has a central reservations, management and location system (CRMLS) in communication through a communications network with each OBU, the CRMLS performing all reservations and management functions, and being linked to a database containing a location and availability of each of thr vehicles and a rate for rental, the CRMLS also being provided with an allocation manager system for geographically allocating vehicles. In order to access the vehicle, the system also includes a key being borne by the user. The system minimizes the human intervention in the rental process, and is more user-friendly.