Agree to a large extent with what your saying here Keith. Speadsheet fuel monitoring is a little anal for me. The fuel computer, whilst not the most accurate thing on earth in some cases, is quite adiquate for measuring what it's there to measure. It may not give a totally accurate reading of ACTUAL consumption, but if you keep an eye on it you will get an idea if something is going in the wrong direction. A sudden low reading may indicate a fault for instance. Monitoring things on vehicles can save you a lot of cash. How many times do you read "Car boiled over without reason" on here. Now sometimes they do, sudden failure is always possible. But mostly there is a cause and effect. Checking the water level every week may never produce any water loss. But the one time it does should ring a bell, same with oil levels. As i said earlier speadsheets are a little anal but if you put £20.00 in your beast every other day and suddenly it fell to every day with the same mileage, you would surely be looking for a reason why.