By the way, I just did some Excel manipulation of a copy of the greenhybrid tank spreadsheet I downloaded yesterday afternoon. First, I took the "distance" column and divide it by the "mileage" column and rounded it off to one decimal place. This gives me the gas consumption per tank. Then I use Excel subtotal function to give me a total gas consumption per car. Lets look at some real high mile entries in the database:

EMAXX: total gas from db: 307.7, total gas per calculation: 315, mpg difference: 60.1 vs 58.7.
City: total gas from db: 130.7, total gas per calculation: 132, mpg difference: 58.43 vs 90.07.
Little Red Beauty: total gas from db: 318.4, total gas per calculation: 323.6, mpg difference: 91.5 vs 90.07.
Sparky: total gas from db: 221.1, total gas per calculation: 221.4, mpg difference: 57.3 vs 57.26.
Keeps on rollin': total gas from db: 288.8, total gas per calculation: 290, mpg difference: 54 vs 53.82.

So the difference seem to be uneven. Interesting eh?

By the way, I did double check all the individual tank numbers above between the db and my working spreadsheet. They are exactly the same. So difference is completely in summing the tanks to a car total.

Comments?

Andy