[lupinsea]

I used to do that for my cars. For about 3-4 years I kept meticulous records at every single fill up. It was something simple and small, 8.5x11" paper folded in quarters and kept in the glove box with a pen.

The categories:

date | milage | gallons | price/gal | notes


About every 1-3 months I'd enter the data into an Excel spread sheet and this was my maintenance log, too. Simple formulas could be set up to calculate the MPG based on the milage and gallon data. I might have had a formula to figure total fill up cost. The key was to top off the gas tank at each fill up to get accurate MPG calculations later. Which wasn't a big deal for me since I figured I'd burn up the gas eventually so I might as well top off.

In the "Notes" category would be anything of note such as any maintenance or repairs (and their cost) that were performed during that tank of gas (usually 250-ish mile interval). I figured that was good enough accuracy for my records.

Anyways. It was interesting looking back and seeing fluctuations in gas prices and such. Or the 10 mpg drop in fuel economy where I was having some fun on California Hwy 1 on a road trip.

Eventually I stopped doing this about the time I got the BMW. But for about 3-4 years I kept it up.