Personal Gas Logs

[instarx]

Actually, because the multiplication has to be done before the addition I'd write it this way:

(($4.39 * 1 gallon) + ($3.99 *10.25 gallons)) / total gallons

therefore

(4.39 + 40.89) / 11.25 = $4.025

The Excel equation would be

=((4.39*1)+(3.99*10.25))/(1+10.25)

Note the double parentheses in the numerator.

[Piwoslaw]

In my fuel log I input the number on the main odometer, then I get the kilometers driven by subtracting. I think this should be done in the EM garage: you input how much fuel you bought (and for how much), your odo, and the date. The way it is now I always wonder whether I should input how much I tanked up, or estimate how much I used since last fill up? This wouldn't be a problem if I always filled up when almost empty, but sometimes I fill up only half the tank, sometimes I use an automatic gas station with prepaid cash (so I can't know exactly how much I have to pay to get up to full).

[tasdrouille]

Originally Posted by mhmitszach

Let's see it!

City mpg of other vehicle to compare to = cmpg
Highway mpg of other vehicle to compare to = hmpg
Distance driven = D
% of tank driven in the city = %C
Cost per gallon = $G
Cost of fillup = $C

((D/cmpg*%C)+(D/hmpg*(1-%C)))*$G-$C = $ saved (or lost) vs driving an other vehicle with properties cmpg and hmpg.

instarx, priority rules for arithmetic say * takes precedence on + so the double parenthesis aren't really needed. But for those who could be confused it removes all doubt, I agree.

[instarx]

Originally Posted by Piwoslaw

In my fuel log I input the number on the main odometer, then I get the kilometers driven by subtracting. I think this should be done in the EM garage: you input how much fuel you bought (and for how much), your odo, and the date. The way it is now I always wonder whether I should input how much I tanked up, or estimate how much I used since last fill up? This wouldn't be a problem if I always filled up when almost empty, but sometimes I fill up only half the tank, sometimes I use an automatic gas station with prepaid cash (so I can't know exactly how much I have to pay to get up to full).

Piwoslaw, being in Poland you might be interested in this site: Spritmonitor which does all that and also allows you to indicate partial fill-ups. Click on the mpg icon below in my sig to see my data.

If you look at my log you will see that I had a partial fill-up on august 8 last year when I was mixing E85 ethanol and gasoline to get E10. The program took it in stride so it will deal with partial fill-ups at prepaid stations with no problem. Just enter mileage, gallons and cost and everything is figured. You can also compare your mileage to others with the same car. It is the easiest and most useful mileage/expense tracker I have ever used.

There is a small glitch in that the data you see as a visitor to my data is presented in liters, and the $ amounts are labeled EUR. But when logged in everything is right.

[trikkonceptz]

Fuelly | Share and Compare Your MPG is also a pretty good site, in that it keeps averages for price paid per gallon/liter as well as tracking your annual expenditure in fuel costs. It too has a check box to indicate partial fill ups and allows you to search out similar vehicles for comparison. It registers cost per mile too.

I find it pretty informative.

[Thalass]

Here's mine. Everything is in km and L, except the mpg column of course.

The second sheet is full of little calculators and things, and the third sheet is the repository for previous years' totals/averages.