Enter in Partial Fill-Ups

[ozreiuosn]

Complete Fill-Up every time? Fuelly is caculating my MPG wrong due to my partial fill-up.

I put some gas into my car last night, only about 2 gallons, but Fuelly went ahead and assumed that I went my 355 miles on 2 gallons. So my question is am I allowed to enter partial fill ups? Maybe we need a check box allowing such? Or did I hit a bug?

Date: 8/19/08

Miles driven since last fill up: 355.0

Gallons bought: 2.040

Price per gal: $4.09

Estimated MPG: 174.0

Yeah...I wish I got 174 MPG

[pb]

We're adding a partial fill-up option today. We're planning to have it added to the site before the end of the day.

[ozreiuosn]

Thank you! Ill just delete that entry and redo it when you add the feature.

[pb]

Partial fuel-ups are available now.

[ozreiuosn]

I don't understand why a partial fill up can't calculate the MPG if you're putting in an odometer reading every time.

If I put 2 gallons in for a partial fill up and I went 70 miles I got 35mpg.

[mathowie]

ozreiusn, I explain the way fuel ups work in calculating mileage on another thread.

If you don't fill up a tank all the way, it simply doesn't work even if you are using odometer. The problem is you can drive 300 miles and only get 2 gallons. Your next fuel up might be 10 gallons after only 40 miles (to make up for the low fuel), but the non-fillup and followup throw your average completely off.

Here is a spreadsheet with test data, assuming I have a 20 gallon tank and my car always gets 20 mpg (and the odometer started at zero with the first fill-up).

You can see from the data that the non-fillup throws the MPG way off into the 150mpg range, and the subsequent 2.67mpg fill up doesn't bring the average back to 20mpg