I just deleted and reinstalled and got the same problem, but this time it showed 0 twice as B3NN3TT noted, I never noticed that before. I've attached screen shots from before I deleted and when I just tried the test one.
Either way, the fuel ups always sync and eventually update to show actual MPG. If I sign onto the full site, it is always right, even if I do it right away.
The first 4 are before, the last 4 are after.
I left the test in for now, it shows 93mpg
on the website. After closing and reopening the app it also updated to show.
It's been doing this for a while, I think after one of the updates. It seemed to work fine before that. Unfortunately I didn't bother noting as I assumed it would be fixed with the next iteration, but I guess if no one tells you the problem, you can't fix it eh