Partial Fuel-Up distorts MPG
 

I recently drove almost 500 miles and then put in only 5 gallons (partial fuel up). I entered that in fuelly including checking the "partial fuel-up" box. Fuelly went ahead and calculated and displayed my new average mpg as if it had been a full fuel-up, greatly (and inaccurately) increasing the displayed mpg. If that "partial fuel-up" box is checked, fuelly should (1) remember the gallons added (for use later) and (2) not change the displayed average mpg. FYI, I deleted that partial fuel-up.

You may have accidentally unchecked the box again. As far as I'm aware, the partial fuel up box is working as designed, it shouldn't calculate the MPG for that fuel up, or the subsequent couple after that. Try adding it again and make sure the box is checked, it should work fine.

I added that partial fuel-up again, making sure the "partial" box was checked. As before, it calculated and displayed the new (incorrect) average mpg, both on the fuelly page and also displayed with my posts to fordfusionhybridforum.com . I then looked at that fuel-up via "Edit" and the "partial" box was still checked. I again deleted that fuel-up.

Looking at your log- 2015 FFH Fuel-up Log | Fuelly
I don't see any partials. If you deleted it already please add it again so I can see what's going on.

I just added a Partial fillup to one of my test vehicles and it stayed checked correctly and did not calculate MPG until I added another full-fillup.

Thanks.

It's back up.

Partials still contribute to your overall average MPG. I'll have freddie double check the math and ensure it's calculating correctly.

In the meantime, I've ignored/hidden the last fillup so it wont affect your averages but that way we can still restore it as needed while troubleshooting.

My point is that partials should not contribute to overall mpg because there is no way to know how much it should contribute,

It's still affecting the average.

It's still taking into account your miles tracked.
It'll settle out once you enter another full fuel-up.
Shouldn't be. I have it currently ignored. Refresh your page.

- But it will be completely wrong until that next complete fuel-up.

- I'm looking at my fuelly signature on fordfusionhybridforum.com and (refreshed) it still shows the incorrect average mpg.