Figures on my account

[rbs4898]

Ok, I may not be the sharpest but I dont believe I am that stupid either and I cannot figure out how I have skewed the figures on my account to give me an MPG of 38 when I know its around 24?

I have put in the details I had for 3 fuel ups, the first a complete one and the others partial, and marked as such. For my mileage I am using the odometer and I am sure that it is with this that I am doing something wrong as the mileage covered is missing out the first fuel up and so is out of sync, giving me inflated figures.

I have attemted to use the contact facility to establish how I have gone wrong and how to correct it but have as yet rec'd no response. Can anyone shed some light on this and point me in the right direction as I would like to make proper use of the site?

Thanks

Rob

[waterboysh]

For the first fill up it has no idea how many miles you drove during that fill up, only how many miles were on the vehicle when you filled up.

For your average then, take the 2nd two and add up the miles and you get 649. Add the number of gallons you used for fill ups 2 and 3 and you get 20.49 gallons. 649/20.49 = 31.7 which is what your fuelly profile shows.

[rbs4898]

Hi, thanks for coming back to me but that isnt quite correct to what has happened.

For the 1st fill up I put in the odometer reading and amount of fuel inc. price etc. When i did the 2nd fill up i entered the same details, current odometer, amount of fuel etc.. By this time I had covered 451 miles, but my account has not allocated this against the fuel purchased at the initial fill up, it has put it against the 2nd, where I purchased less fuel therefore giving me an infalted average.

The reality is I have covered 649 miles in total, but I have done so with the fuel from the first two fill ups (118 litres or just over 26 gallons). The 3rd fill up is still in the car, just about, so I dont know how many miles that will account for. My actual MPG is somewhere around 24.9 not the 38 that Fuelly states.

I just need to understand how to get everything in sync or what I need to put in if I need to restart?

Thanks

[MMUK]

The fuel on your first fill-up is (correctly) ignored when you are set up in Odo mode. Note that you do not get a miles/gallon for the first tank.

On the second fill-up, it compares the odo from the first tank to the odo on the 2nd tank to get miles. It then divides that by the amount of fuel (from the 2nd tank). That gives you miles/gallon for the second tank. However, because it was just a partial, the individual mpg will be hidden and you will only be shown the running total.

On the third tank, it compares the odo from the 2nd tank with the odo from the third tank to calculate miles for the third tank. That is divided by the fuel for the third tank to give you miles/gallon for the third tank. Again, it was just a partial tank so you don't get shown the individual mpg figure.

>...but my account has not allocated this against the fuel purchased at the

>initial fill up, it has put it against the 2nd,...

That's correct, that's what it should do. As waterboy already said, the system cannot not know how many miles you drove on the first tank, because it only has the odo reading from the end of the tank. Hence the amount of fuel that you added for the first tank is irrelevant and will not be used for any calculations.

[rbs4898]

Ok - thanks I am sure I will get my head around it

[MMUK]

Once you start entering full tanks rather than partials it should be a lot clearer (since you will be seeing the individual tank MPGs).

At the moment, because you have only had partials (the first tank doesn't count), fuelly cannot know for sure what your mpg is, because it doesn't have a reliable figure for gallons. But over time, even if you only enter partials, it should average out (it's just a lot quicker with full tanks than partials).

[rsdavis9]

I have a post about how the forum should fix there calcs for partials with odometer. In short the solution I found was to don't do partials. If you enter a partial then the gallons are never include in the total. So what I do when I have a partial is use the gallons to figure out a fake odometer reading and put that in. ex: 7g * 40mpg = 280mi. add the 280mi to the last full fillup odometer reading. Use whatever mpg number that is reasonably close to your avg. Otherwise marking it partial will definitely skew the avg mpg on your car.