A method of estimating the fuel consumption of a vehicle, said method comprising the steps of estimating an overall power of said vehicle, by estimating a rolling power component, an aerodynamic resistance component and an acceleration component, using at least one parameter obtained from an on board diagnostic system of the vehicle; determining the type of fuel used by the vehicle; and estimating said fuel consumption by summing said components of said overall power and dividing by the energy value of said fuel type and by a predetermined engine efficiency value.