1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Computer Calculated MPG and Scangauge II

Discussion in 'Gen 3 Prius Fuel Economy' started by Xterra72, Sep 21, 2017.

  1. Xterra72

    Xterra72 Senior Member

    Joined:
    Oct 20, 2013
    1,410
    1,660
    0
    Vehicle:
    2013 Prius
    Model:
    Persona
    I monitored my 40 minute, 25 mile commute to work today. Mixed traffic and average between 65-70 mph. After reaching my destination, these were my readings.

    The computer read 50.7 MPG
    The Scangauge II read 65.3 MPG

    Is there some calibration needed?
    I'm guessing the computer reading in the car is more accurate.

    Any thoughts?
     
    #1 Xterra72, Sep 21, 2017
  2. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    110,133
    50,050
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    the computer is usually a few percent high, resulting in lower mpg at the pump. not sure what's going on with the scan gauge. did you reset the trip meter on the car before starting out?
     
    #2 bisco, Sep 21, 2017
  3. Xterra72

    Xterra72 Senior Member

    Joined:
    Oct 20, 2013
    1,410
    1,660
    0
    Vehicle:
    2013 Prius
    Model:
    Persona
    @bisco, That could be the case. So I have to reset the trip meter every time?
     
    #3 Xterra72, Sep 21, 2017
  4. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    110,133
    50,050
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    just to compare drives and meters. if you're looking at instantaneous mpg, the car is 3 seconds behind. if you want to compare mpg for a trip, or a tank, you would need both devices starting at zero.
     
    #4 bisco, Sep 21, 2017
  5. OBJ

    OBJ Member

    Joined:
    Jan 15, 2015
    62
    27
    0
    Location:
    Stouffville, Ontario, Canada
    Vehicle:
    2010 Prius
    Model:
    N/A
    Is your ScanGauge setup properly (engine size, tank size, fuel units, etc...?
     
    #5 OBJ, Oct 18, 2017
    WilDavis likes this.
  6. royrose

    royrose Senior Member

    Joined:
    Mar 21, 2009
    1,389
    951
    4
    Location:
    Foot of Pikes Peak
    Vehicle:
    Other Hybrid
    Model:
    Limited
    Are you new to Scanguage? It sounds like you need to calibrate it.

    The next time you fill up, you should go to Fillup, then hit done, then save. Then at your next fillup, go to fillup and see how many gallons the scanguage thought you used. You adjust that figure to match how many gallons you actually put in your tank.
     
    #6 royrose, Oct 18, 2017
    WilDavis likes this.
  7. WilDavis

    WilDavis Senior Member

    Joined:
    Feb 4, 2014
    2,492
    2,154
    49
    Location:
    Top RH Corner of RH Coast on L side of The Pond
    Vehicle:
    2009 Prius
    Model:
    II
    I've found that my SG-II tracks pretty much the same as the MFD in the car, but I also keep an accurate log of how much fuel into the tank, and how many miles the car is driven, and over time they all correspond pretty accurately (…at least to within amounts that really make no difference) ;) (…but as they say YMMV :rolleyes: )
     
    #7 WilDavis, Oct 18, 2017
(You must log in or sign up to post here.)