Recently Leslie contacted me about his web site, MyAutoLog; the site allows you to enter fill-up data from each time you fill your car (fuel cost, quantity and odometer reading) and generates loads of MPG data. The web site is stunningly well designed – even more incredible when you read that all of it is his own work!
I sent Leslie all the MPG data from GBMINI#2 and GBMINI#3 (I maintain an Excel spreadsheet) and he entered it all into his programs:
Leslie entered the before-JCW and after-JCW data for GBMINI#2 as two separate cars; the summary page for “GBMINI” (above) shows GBMINI#2 doing 11.9K miles before the JCW upgrade, at an average 27.80mpg; and 16.5K miles after, at a lower 26.76mpg.
GBMINI#3, with its automatic transmission, is averaging 26.95 on 7.5K miles so far.
More interesting perhaps is the ability to compare your car with everyone else who enters data; here for example I compared GBMINI#3 with all MCs, all MCSs and all JCW MCSs:
Now we can see that the average of all MCs is 32.08mpg (4.5K miles), the average of all MCSs is 25.99mpg (36.8K miles) and the average of all JCW MCSs is 25.15mpg (14.4K miles).
We need more MC owners to sign up to MyAutoLog!
Sadly Leslie has not yet got charts working (like GBMINI#3’s MPG chart); also the way he calculates the MPGs (dividing the latest miles driven by the previous tank of gas) is, in my mind, wrong and generates erroneous MPGs, especially if some of your fills are at significantly different distances apart.
For example his calculations claim a best MPG for GBMINI#2 of over 59mpg! This is caused by filling up the tank before a long drive (so only a small fill), then driving a long way before the next fill (so a large distance).
I always calculate with the latest distance divided by the latest fill, which is more accurate assuming (as I do) that I always fill the tank to the top.
However none of this detracts from the very useful averages and comparisons with other cars.
M&I / GBMINI 
Nice site, really like the graphics, and nice to see he spelled MINI correctly (not Mini) 😉
and he even had the models correct.
The MPG algorithm “error” is a bit disturbing, maybe he’ll allow you to flip a switch to decide in the future?
Chris
Thanks Ian, I appreciate you mentioning MyAutoLog.com on your website. As you stated and we have discussed, the miles/gallon calculation for a single fueling can be skewed when people just top of their tanks but I felt this was necessary so members don’t have to figure out how much of their fuel they had used. In addition, members can enter their fuelings right after they have filled up instead of having to save their receipts until the point when they know how far they traveled. This matters since the next phase of MyAutoLog.com is creating a mobile version so people can save their data at the pump with a mobile device. With all of that said, the miles/gallon calculations over multiple fuelings is much more accurate.
Again, thank you for providing the fueling data on your last two MINIs and the website mention. The more data MyAutoLog.com has to better it is for everyone. I appreciate it.
I use bostongasprices.com (part of gasbuddy.com, and hammered lately due to the this week’s explosion in gas prices), which has a completely free fuel logbook. It doesn’t provide quite the detail, but it does provide charts.
It gets around the partial fillup problem two ways: every time you enter, it asks if you have filled up completely or not. It also records your odometer reading each time instead of relying on you to accurately use your trip meter.
I post my charts monthly on my site:
http://www.jwardell.com/mini/gas.html
Thanks to Josh, I’ve been using sandiegogasprices.com for tracking the new beast’s mpg but myautolog looks good. I agree though that the calculation seems wrong but I’ll check it out and maybe I can spring $4 for a year….
I had been using MyAutoLog for a while but had stopped updating it. I did just go back and enter my last 10 or so fuelings in.
I agree that the methodology regarding mileage is wrong. The actions of the future have no reagrds to a previous tank.
However, over the long haul, I guess it averages out. In about 9 months of keeping my mileage there and in a seperate spreadseet, the spreadsheet is at 21.4 and Myautolog is 21.3
As for the chart in excel. I am an excel idiot when it comes to graphs. Is there an easy explanation as to how to make a graph like you have Ian?
Hello Lee. I’m glad to hear MyAutoLog.com was very close to your own results. Keep in mind the future (next) tank is only used to determine how many miles the previous tank traveled. That’s it. When MyAutoLog.com calculates miles/gallon for multiple fuelings it divides total miles by the total gallons for all of those fuelings. The miles/gallon values for each individual fueling are ignored. In fact, they are only calculated for those members who are interested in knowing what the miles/gallon was for the fueling they just completed.