FUEL CONSUMPTION

1 . A method of estimating fuel consumption of a combustion engine in a vehicle during operation of the combustion engine with a fuel type, the method comprising:

obtaining a value for air flow through the combustion engine;

determining an amount of oxygen that is burned during operation of the combustion engine by, based upon the value for the air flow,

estimating the quantity of oxygen flowing through the combustion engine, and

estimating the amount of the oxygen flowing through the combustion engine that is unburnt; and

estimating the fuel consumption based upon the determined amount of oxygen that is burned and the fuel type.

2 . The method of claim 1 , wherein determining the amount of oxygen that is burned includes subtracting the estimated amount of oxygen flowing through the combustion engine that is unburnt from the estimated quantity of oxygen flowing through the combustion engine.

3 . The method of claim 1 , wherein estimating the amount of the oxygen flowing through the combustion engine that is unburnt includes analysing exhaust gases and determining therefrom an amount of unburnt oxygen in the exhaust gases.

4 . The method of claim 1 , wherein estimating the quantity of oxygen flowing through the combustion engine includes obtaining or estimating airflow through the combustion engine, for a particular time interval, at successive time intervals.

5 . The method of claim 4 , wherein estimating the quantity of oxygen flowing through the combustion engine includes acquiring data from an On Board Diagnostics (OBD) system of the vehicle during the successive time intervals, each time interval being defined by one of a plurality of reporting cycles of OBD system.

6 . The method of claim 5 , wherein the steps of obtaining, determining and estimating are carried out as the combustion engine propels the vehicle along a surface while the vehicle travels between respective geographical locations.

7 . The method of claim 1 , wherein the steps of obtaining, determining and estimating are carried out as the combustion engine propels the vehicle along a surface.

8 . The method of claim 1 , wherein estimating the fuel consumption includes:

estimating fuel mass being used by the combustion engine by dividing the value for the air flow by a stoichiometric ratio associated with the fuel type; and

estimating the fuel consumption based on the estimated fuel mass and the determined amount of oxygen that is burned.

9 . The method of claim 1 , wherein estimating the fuel consumption includes:

estimating an overall power value for operating the vehicle;

obtaining an energy value of fuel used by the vehicle; and

dividing the overall power value by the energy value of the fuel and by a predetermined efficiency value attributed to the combustion engine.

10 . The method of claim 9 , wherein estimating the overall power value includes summing estimated respective values, for the vehicle, of a rolling resistance power component, an aerodynamic resistance power component and an acceleration power component.

11 . The method of claim 9 , wherein estimating the fuel consumption includes:

determining upper and lower estimates of mass of the vehicle based upon the estimated overall power value,

determining upper and lower limits on fuel consumption based on the upper and lower estimates of mass of the vehicle, and

estimating the fuel consumption using the upper and lower limits on fuel consumption as upper and lower bounds.

12 . The method of claim 1 , wherein obtaining the value for the air flow rate includes calculating an estimate of the air volume flow rate based on a size of the combustion engine and a speed of operation of the combustion engine.

13 . A method for dynamically estimating fuel consumption of a vehicle during a journey during which the vehicle travels between geographical destinations via power provided by an engine burning fuel in the vehicle, the method comprising:

for each of a plurality of successive time intervals during the journey,

obtaining airflow through the engine,

estimating fuel mass processed by the vehicle during the time interval by dividing the obtained airflow by a stoichiometric ratio associated with a type of the fuel,

determining an amount of oxygen burned by the engine during the time interval,

estimating a fuel consumption value based on the estimated fuel mass and the determined amount of oxygen burned; and

providing an indication of fuel consumption during the journey based upon the estimated fuel consumption for the plurality of successive time intervals.

14 . The method of claim 13 , wherein determining the amount of oxygen burned by the engine during the time interval includes estimating the quantity of oxygen flowing through the engine based on the obtained airflow and an amount of unburned oxygen in exhaust of the vehicle.

15 . The method of claim 14 , wherein determining the amount of oxygen burned by the engine includes acquiring data from an On Board Diagnostics (OBD) system of the vehicle during the successive time intervals.

16 . An apparatus comprising:

a first circuit module configured and arranged to obtain a value for air flow through a combustion engine in a vehicle during operation of the combustion engine with a fuel type;

a second circuit module configured and arranged to determine an amount of oxygen that is burned during operation of the combustion engine by, based upon the value for the air flow,

estimating the quantity of oxygen flowing through the combustion engine, and

estimating the amount of the oxygen flowing through the combustion engine that is unburnt; and

a third circuit module configured and arranged to estimate the fuel consumption based upon the determined amount of oxygen that is burned and the fuel type.

17 . The apparatus of claim 16 , wherein the second circuit module is configured and arranged to determine the amount of oxygen that is burned by subtracting the estimated quantity of oxygen flowing through the combustion engine that is unburnt from the estimated quantity of oxygen flowing through the combustion engine.

18 . The apparatus of claim 16 , wherein the third circuit module is configured and arranged to estimate the fuel consumption by:

estimating an overall power value for operating the vehicle;

obtaining an energy value of fuel used by the vehicle; and

dividing the overall power value by the energy value of the fuel and by a predetermined efficiency value attributed to the engine.

19 . The apparatus of claim 18 , wherein the third circuit module is configured and arranged to estimate the overall power value by summing estimated respective values, for the vehicle, of a rolling resistance power component, an aerodynamic resistance power component, and an acceleration power component.

20 . The apparatus of claim 16 , wherein the third circuit module is configured and arranged to estimate the fuel consumption by:

estimating fuel mass being used by the engine by dividing the value for the air flow by a stoichiometric ratio associated with the fuel type; and

estimating the fuel consumption based on the estimated fuel mass and the determined amount of oxygen that is burned.