Won't MPG data be skewed if not filling from 0 to 100% every time? - Fuelly Forums

Click here to see important news regarding the aCar App

Reply
 
Thread Tools Display Modes
 
Old 12-06-2018, 05:01 PM   #1
Registered Member
 
Join Date: Nov 2018
Location: England
Posts: 26
Country: United Kingdom
Question Won't MPG data be skewed if not filling from 0 to 100% every time?

Surely Fuelly can only figure out the MPG if you fuel the car from 0% to 100% every time, as it's based on the amount of fuel going into the car times by the odometer reading?

The issue is, no car is at 0% every time you fill up.

If it's at 10% (which is probably when most people go to fill up), would the MPG data not will be skewed, therefore meaning it's probably preferable to just rely on a car's LCD MPG data?

Just a thought. I may be wrong.
__________________

kingmustard is offline   Reply With Quote
Old 12-06-2018, 09:14 PM   #2
Registered Member
 
Join Date: Jun 2017
Posts: 1,461
Country: United Kingdom
Location: Danderhall
You are wrong. As long as you fill to the same point every time, in my case first click off of the pump, and note the mileage either by trip miles or odometer reading, since last top up, then you can calculate the mpg. If I add 2 gallons to the tank to fill it, and have done 100 miles since the last time I filled it, I get 50 mpg. It doesn't matter if I have a 7 gallon tank with 5 gallons remaining before top up, or a 10 gallon tank with 8 remaining.
I have an on-board reading, plus a ScanGauge E, and all 3 figures are noted every top up. They are all slightly different to each other, but the calculated figure is the most accurate figure. The more you record, the more accurate it gets.
__________________

__________________
2009 Skoda Fabia Elegance 1.4 16V
JockoT is offline   Reply With Quote
Old 12-06-2018, 11:13 PM   #3
Registered Member
 
Join Date: Aug 2009
Posts: 3,385
Country: United Kingdom
Location: Mid Wales
As the poster above says, so long as you top up every fill up, regardless whether you've done 5 miles or 555 miles, you'll still get an idea of how much fuel you just used. Partials where you don't fill up to the top are less accurate, you have to wait until the next time you fill up to get a figure, but the fuel you put in and the miles still contribute.
__________________



Please subscribe to my YouTube channel
Draigflag is online now   Reply With Quote
Old 12-06-2018, 11:39 PM   #4
Registered Member
 
Join Date: Jun 2017
Posts: 1,461
Country: United Kingdom
Location: Danderhall
As Draigflag says, as long as you tally the amount of fuel added and the miles driven you can calculate the average mpg for that period. Last year I drove 8910 miles and put in 161.3 gallons of fuel. This calculates out at 55.24 mpg. My average Fuelly figure of 54.4 mpg (as of Dec 2018) is since I acquired the car in July 2016.
__________________
2009 Skoda Fabia Elegance 1.4 16V
JockoT is offline   Reply With Quote
Old 12-07-2018, 03:57 AM   #5
Registered Member
 
Join Date: Nov 2018
Location: England
Posts: 26
Country: United Kingdom
Question

A potential issue.

I created an account on Fuelly a few days ago (early December).

I have yet to refuel my car since creating the account.

I have, however, added the previous known odometer readings as Notes:
  • 01/11/2012 - 0 miles
  • 18/12/2012 - 949 miles (service)
  • 25/10/2013 - 8337 miles (service)
  • 19/10/2015 - 27,689 miles (MOT)
  • 30/12/2015 - 28,662 miles (service)
  • 11/01/2016 - 28,662 miles (MOT)
  • 29/07/2016 - 38,014 miles (service)
  • 21/01/2017 - 46,465 miles (service)
  • 13/05/2017 - 46,492 miles (MOT)
  • 02/11/2017 - 48,988 miles
  • 10/05/2018 - 52,099 miles (MOT)
  • 29/07/2018 - 54,355 miles
  • 26/10/2018 - 57,155 miles
When I go to New Fuel-Up Record, it shows "Previous Odometer" as 57,155 but that was not recorded when I last refuelled.

If Fuelly starts to base my MPG on 57,155, won't it be inaccurate from the start?
kingmustard is offline   Reply With Quote
Old 12-07-2018, 06:02 AM   #6
Registered Member
 
Join Date: Jun 2017
Posts: 1,461
Country: United Kingdom
Location: Danderhall
Just start your first fill up with the current odometer reading. It will be greater than 57,155. It will start from that odometer reading for your future mpg readings.
__________________
2009 Skoda Fabia Elegance 1.4 16V
JockoT is offline   Reply With Quote
Old 12-07-2018, 06:05 AM   #7
Registered Member
 
Join Date: Aug 2009
Posts: 3,385
Country: United Kingdom
Location: Mid Wales
Wait you've done nearly 60,000 miles and haven't recorded a single fuel up?... I think you missed the point of fuelly.
__________________



Please subscribe to my YouTube channel
Draigflag is online now   Reply With Quote
Old 12-07-2018, 06:05 AM   #8
Registered Member
 
Join Date: Nov 2018
Location: England
Posts: 26
Country: United Kingdom
Thumbs up

Quote:
Originally Posted by JockoT View Post
Just start your first fill up with the current odometer reading. It will be greater than 57,155. It will start from that odometer reading for your future mpg readings.
Ah, Fuelly bases MPG solely on refuels and not Notes, then?

Excellent

Quote:
Originally Posted by Draigflag View Post
Wait you've done nearly 60,000 miles and haven't recorded a single fuel up?... I think you missed the point of fuelly.
There's no reason to only start using the app when I first buy a new car.
kingmustard is offline   Reply With Quote
Old 12-07-2018, 06:58 AM   #9
Registered Member
 
Join Date: Jun 2017
Posts: 1,461
Country: United Kingdom
Location: Danderhall
I only found Fuelly recently myself. Luckily I had dates and fuel ups recorded in Excel so I added them retrospectively.
__________________

__________________
2009 Skoda Fabia Elegance 1.4 16V
JockoT 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 iOS Apps
No Threads to Display.
Powered by vBadvanced CMPS v3.2.3


All times are GMT -8. The time now is 12:11 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.