Fuel Formula per day

How do I calculate the fuel consumption per day one of our vehicles?

eg : We have an Hyundai loader which refilled on the 02/07/08 200 ltrs (fuel) at 12:00pm, the meter reading at that time was 1292km. On the next day, 03/07/08 it was refilled another 200 ltrs at 12:00pm and the meter reading was 1300km.

Please I need this information because I have to provide a weekly report to the boss for all our vehicles consumption on fuel.

From a vehicles fuel consumption point of view, during one day (during 02/07/08 12:00 - 03/07/08 12:00), it has consumed 200 ltrs to driven 1300km-1292km=8km. But from a economical point of view, during 02/07/08 12:00 - 03/07/08 12:00, the company has bought 400 liters of fuel for that vehicle.

...with all that information, it sounds like school assignment ;-)
//Ola