Unattended fleet vehicle security system and method

A communication system (10) and method (200, 300, 400) to allow authorized access to a vehicle (12). The system communicates with an internet server (14) and a mobile communication device (18) such as a smart phone (22) or RFID transponder (20) to determine if a person (16) attempting to access the vehicle (12) is authorized. The system includes an in-vehicle security module (24) configured to be installed on the vehicle (12) and to receive an authorization signal (26) from the internet server (14). The in-vehicle security module (24) includes a keyless entry transmitter (34) configured to communicate with a keyless entry system (38) of the vehicle (12) effective to allow access to the vehicle (12) if the authorization signal (26) is received. By using a keyless entry transmitter (34) to operate the vehicle's security system, the communication system (10) is easy to install as opposed to systems that require a wired interface with the vehicle (12). Such a system is useful for unattended operation of vehicle (12) rental fleets or employee vehicle (12) fleets.