Having just gone through all my old fuel reciepts, I decided to make a little web-based application to track and graph fuel economy for my vehicles. I've been recording the following on fill-ups (among other things):
- odometer reading
- time/date
- volume added to the tank.

The details are not that important other than to say that I have the data in a couple database tables and indexed, etc (for you computer geeks like me). I can sort it however I want. I'm trying to figure out a good general formula to give approximate mpg based on those numbers for generating datapoints on a graph.

I considered doing a simple "it took this much to fill up the tank and my last mileage readin was X" type thing, but then the thought occured to me that I don't ALWAYS fill up the tank, so it might be better to get my delta value over a couple fill-ups. It might not give me any more accurate individual results, but the curve, when plotted should be better over time.

So, what are y'all doing for your tracking? Spreadsheets? hand calculations, SQL with a web frontend like me?

Dan

Back in my Sophomore year of college I had to design a java applet to display an average of miles driven to fuel used over the course of 10 fuel-ups, I'll attach the link here if anyone feels like typing in 10 times their fuel use...otherwise use a calculator and type miles(km) driven divided by gallons(litres) used...enjoy...of course if you type in an error in my applet you won't be able to go back unless you refresh the page..i think, been a long time since I fooled around with Java Programming...

Applet Here

If you like Battleship, give this a shot...make sure you have someone to play against though, or you can check it out for fun...

Battleship, Java Style

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Had 2005 KJ Rocky Mnt. Edition (destroyed)
Had 2006 KJ Sport 4x4
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Southern L.O.S.T. # 236487

Yeah, that gives a good average. Looks like (sum(miles(1-n))) / (sum(gal(1-n)))

What I'm looking for is a general math smippet that'll appoximate instantaneous milage based on deltas from the current odometer and the previous based on the number of gallons added (and possibly the past couple to normalize the data).

Man, I wish I had a copy of the moonlander applet I did way back when(polygons with gravity, thrust, and solar wind calculations controled via keyboard to land on a pad on the screen).

Dan

A nice simple Excel trick is to go into Tools/Add-ins and add Statistical functions (you may have to have original disks) -
This will allow you to do an EWMA (Exponentially Weighted Moving Average) -
Generate an EWMA SPC chart weighing the last 3-4 tanks for each chart data point - plot your mileage on the SPC chart.
This should allow some variation for an incomplete fill of 1 tank - and yet still give you a response if something is changing.

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2005 CRD
stuff
Skeptic quod gratis asseritur, gratis negatur

I LET THE ON-BOARD COMPUTER DO MY MATH FOR ME....
ANYTHING WRONG WITH THAT???

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WGNMAN- in a RENEGADE
NUFF SAID...

No, nothing wrong with that, but ya don't hafta shout it

I normally try to do a complete fill each time and just do the standard x miles / y gallons = mpg. I suppose if I kept reasonably accurate records of miles at each fill and number of gallons I could do a better long-range average, may have to try it to see what I get.

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Kevin
AD5VG
Just another red Jeep in the world...
L.O.S.T. #KB051963

and reading a simple number is so boring compared to a good SPC chart......

(and you have to have the EVIC - that was an option - not standard)

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2005 CRD
stuff
Skeptic quod gratis asseritur, gratis negatur

...well, if you have an EVIC then I suppose not...however...


dagmabbit...that'll teach me for clicking reply then going for a walk before hiting "submit"...

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2K9 Space Grey 335d Sport
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