"Partial fill-up" is calculated
 

When I added my 95 Suburban my first fill-up (just got the truck) was a partial fill up. I checked the box for that, assuming that it would NOT count that since the first fill up being a partial fill up would not contribute to the data. Then I did another fill up to fill the tank, and it calculated 1MPG. This thing might be a gas-guzzler, but it's not THAT bad. I deleted the first partial fill up so only the full tank is there now, but I must wait until the next complete fill up to calculate the (lack of) fuel economy.

I think that if the first fill up in Fuelly for a particular vehicle is partial, it should not be counted towards MPG calculation.

Partial fill-up is for when you add fuel to the tank but you don't pump to FULL. It is not intended for when you don't add from empty, or for when you get your new car. I have specifically asked for an "Initial Fill-Up" setting in the past pointedly to address the situation of when you first get your vehicle. I've had to work around the lack of option by manipulating odometer values and such until I get it to where it's tracking my driving correctly.

It's a pain with new vehicles, it's a giant pain with used ones.

I was gonna ask for the same but I guess I have my answer. this is stupid !