[Nepenthe]

Here's my file for calculating all things gas related. It has my first few fillups already so you'll have to delete those. Basically you enter the information in the red spots, including the date, the number on the trip ODO (or main ODO, it doesn't matter -- I use one trip ODO to reset to 0 at every fillup and one to collect mileage since purchase, and my main ODO is 50 miles higher than trip A, so you can adjust accordingly to your car), the gallons purchased, the number of days since last fillup (it doesn't do this automatically right now), and the price per gallon, and it spits out miles accrued, MPG, miles/day, miles/year (at that rate of consumption), total cost, $/mile, $/day, and $/year (at that rate).

It also keeps the averages, and at the bottom of the first tab the sum of what you've paid for gas. Currently you do have to update the other red cell, F3, basically changing it from F8 to F9 for the next fillup, then F10, and so on, for the averages line to work right. Note also I'm not including my first fillup (line 6) in most of the calculations, only the next two fillups.

The other tabs have various graphs.

You may have to rename the file after saving to your computer, rename the part after the . to "zip" and then double click on it to drag out the Excel file.

I always buy my gas at the same station and pump when possible.