A fuel measuring device, for mounting on the inlet to a vehicle fuel tank, has a sensor for recording a flow rate of fuel flowing through the inlet into the vehicle fuel tank. A processor for integrating the fuel flow rate to determine amount of fuel supplied to the fuel tank and a data storage device, for storing data indicative of the volume of fuel supplied to the vehicle fuel tank, are provided. A connector, for enabling the stored data on fuel volume to be transferred from the fuel measuring device on the vehicle to another device separate from the vehicle. A signal from a sender unit of a vehicle fuel tank may be used. A related method enables fuel usage to be tracked by, for example, the renter of a vehicle, and a further related method provides improved fuel gauges for use in fleets of rental cars.