Abstract: A fuel consumption device is suitable for insertion into a diagnostic port of a motor vehicle. The device is operable to receive a fuel gauge signal and one or more powertrain signals. The device estimates fuel consumption based on said one or more powertrain signals and uses the estimated fuel consumption data to generate a fuel consumption database. The database indicates a relationship between a fuel gauge signal and actual amounts of fuel. Upon detecting a refueling event, the device consults a fuel consumption database to determine an estimated amount of fuel associated with the refueling event. The powertrain signals may include a mass air flow signal. The device may be able to store the fuel consumption database locally and transmit the database remotely. The device is still further preferably operable to record and transmit a record of the refueling event that includes an estimated amount of fuel.