Partial Fill Screws Up MPG Calc... - Fuelly Forums

Click here to see important news regarding the aCar App

Reply
 
Thread Tools Display Modes
 
Old 07-21-2020, 03:25 PM   #1
Registered Member
 
Join Date: Apr 2014
Posts: 45
Country: United States
Location: Burlington, CT
Partial Fill Screws Up MPG Calc...

...once you get back to a filled tank.

Why does Fuelly add in the previous gallons of fuel but doesn't bother to add in the previous miles? This is flat-out stupid!

Partial Fill done on 6/26/20 with 312 miles driven and 7.695 gallons of gas.
Full Fill done on 6/29/20 with 181 miles driven and 13.837 gallons of gas.

Fuelly added the fuel together to get 21.532 and then calculated that amount of fuel used over ONLY the 181 miles for the full fill, resulting in 8.41MPG (and nothing entered for the previous fill).

I am completely confused at how the "math" for this site works and have always complained that two consecutive full fills were NOT necessary to calculate MPG so long as at least one full fill had been recorded somewhere in the past. Now I understand why two consecutive ones are required - it's because Fuelly isn't smart enough to track both miles AND fuel quantity as cumulative.

SMH
__________________

ember1205 is offline   Reply With Quote
Old 07-21-2020, 10:35 PM   #2
Registered Member
 
Join Date: Aug 2009
Posts: 3,077
Country: United Kingdom
Location: Mid Wales
I don't think you entered it properly, I saw the fuel up in question and the amount of fuel you put in on that fuel up is too high. Its even higher than some of your previous tank. A partial fuel up is when you don't fill the tank right to the top, example, you only put a gallon or two in because you want to use a cheaper filling station further down the road.
__________________

__________________



Please subscribe to my YouTube channel
Draigflag is offline   Reply With Quote
Old 07-22-2020, 03:52 AM   #3
Registered Member
 
Join Date: Apr 2014
Posts: 45
Country: United States
Location: Burlington, CT
Quote:
Originally Posted by Draigflag View Post
I don't think you entered it properly, I saw the fuel up in question and the amount of fuel you put in on that fuel up is too high. Its even higher than some of your previous tank. A partial fuel up is when you don't fill the tank right to the top, example, you only put a gallon or two in because you want to use a cheaper filling station further down the road.
I'm not sure how you reached that conclusion...

Full tank
Drive 312 miles (tank is close to empty), but only add 8 gallons, tank about half full.
Drive 181 miles, fill tank (close to 14 gallons).

The tank starts full. I drive a full tank's worth but only bring it back to half. This fill-up is marked partial and it calculates no MPG. Drive until tank is close to empty and completely fill.

Fuelly calculates the MPG using ALL of the gas added but only the most recent miles. If you add the fuel and miles together from the partial and the complete fill and average them, you get almost 23MPG which is roughly what would be expected.
ember1205 is offline   Reply With Quote
Old 07-22-2020, 06:11 AM   #4
Registered Member
 
Join Date: Aug 2009
Posts: 3,077
Country: United Kingdom
Location: Mid Wales
The 312 mile tank is the partial one, the one after, 181 miles, is a regular fuel up, you can't have gotten that much fuel in after a short distance. With method of tracking are you using?
__________________



Please subscribe to my YouTube channel
Draigflag is offline   Reply With Quote
Old 07-22-2020, 06:21 AM   #5
Registered Member
 
Join Date: Apr 2014
Posts: 45
Country: United States
Location: Burlington, CT
Quote:
Originally Posted by Draigflag View Post
The 312 mile tank is the partial one, the one after, 181 miles, is a regular fuel up, you can't have gotten that much fuel in after a short distance. With method of tracking are you using?
The tank before wasn't full. So, yes, I absolutely could put that much fuel into the tank for the complete fill. Re-read my follow up post to understand the process...

I had a full tank and drove until almost empty. Partial fill. Drove until almost empty (which is going to be a much shorter distance since I wasn't starting with a full tank). Filled the tank.

I track by odometer.
ember1205 is offline   Reply With Quote
Old 07-22-2020, 09:04 AM   #6
Registered Member
 
Join Date: Nov 2007
Posts: 1,699
Country: United States
Location: north east PA
Previous partial fills were calculated correctly.
This is probably a bug that came up with a recent update.
trollbait is offline   Reply With Quote
Old 07-22-2020, 09:08 AM   #7
Registered Member
 
Join Date: Apr 2014
Posts: 45
Country: United States
Location: Burlington, CT
Quote:
Originally Posted by trollbait View Post
Previous partial fills were calculated correctly.
This is probably a bug that came up with a recent update.
Yes, I did notice that a previous partial and complete fill combo did seem to calculate correctly. Are the calculated values stored and retrieved when viewing a page? Why aren't they calculated each time? I would think that partial/full fill combos would be either all correct or all incorrect.
ember1205 is offline   Reply With Quote
Old 10-13-2020, 12:52 AM   #8
Out of Fuel
 
Join Date: Oct 2020
Posts: 87
Country: United States
Location: Tampa, FL
Hmm, I wonder if OP was already able to solve this.
EddWick is offline   Reply With Quote
Old 10-13-2020, 04:42 AM   #9
Registered Member
 
Join Date: Apr 2014
Posts: 45
Country: United States
Location: Burlington, CT
Quote:
Originally Posted by EddWick View Post
Hmm, I wonder if OP was already able to solve this.
It really isn't my problem to fix...
ember1205 is offline   Reply With Quote
Old 03-12-2021, 01:16 PM   #10
Registered Member
 
Join Date: Apr 2014
Posts: 45
Country: United States
Location: Burlington, CT
Just to add a little more info to this...

I have recently discovered that entering the data via the mobile app (which appears to be nothing more than a slimmed down version of the web site) causes an MPG calc issue once you finally fill the tank. And, all you have to do is edit the fill-up from a web browser and save it and the MPG calc gets corrected.

Data:

Fill tank
Drive 300 miles
Partial Fill 0 no MPG calc
Drive 150 miles
Fill tank - MPG uses total miles driven divided by only current gallons (this time, it calculated 7MPG).

View history for the car using a computer / web browser and there's an icon stating that the current MPG info include the prior partial fill data.
Click the pencil icon to edit the full fill-up.
Click Save.
MPG now shows 22MPG.

Something is wrong with the way the system is calculating MPG. It -appears- that it's calculating MPG at the time that the record is saved and storing the number instead of actively calculating when the history is displayed. Editing and saving the record using a web browser is clearly doing something differently than when the info is initially calculated using the app...
__________________

ember1205 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Fuelly Android Apps
Powered by vBadvanced CMPS v3.2.3


All times are GMT -8. The time now is 10:43 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.