An automated vehicle rental system with individual vehicle transmitting sensors for keeping track of vehicle mileage, fill state of vehicle fuel tank, and localized position status in a rental lot. Sensors are linked to the vehicle odometer reading and to the vehicle fuel tank float sensor with compensation for types of driving and fuel fill-ups which affect float level readings. The sensors are integrated with or are linked with communicating tags operable in a defined site for ultimate communication of stored vehicle related sensor data, vehicle location and type to a central data base for automatically completely effecting check out, charges and state of vehicle readiness for renewed rental. The transmitting sensors are adapted to avoid interference between sensors of other vehicles during multiple transmissions. Also included is an in-vehicle check out and payment device operatively linkable to the transmitting sensor of the vehicle.