TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker and becoming a Supporting Member. For more info: Support TMC

Speedometer Accuracy?

Discussion in 'Model 3: User Interface' started by ratsbew, Aug 12, 2018.

  1. ratsbew

    ratsbew Member

    Joined:
    Mar 3, 2012
    Messages:
    717
    I set up a GPS speedometer app on my phone and it reported about 1mph slower than what Model 3's speedometer reads.

    Honestly, I'm quite disappointed in this. If I see a number, I expect it to be accurate. You'd think that the car would use GPS to calibrate the speedometer like my bicycle computer does.
     
    • Funny x 7
  2. SSedan

    SSedan Member

    Joined:
    Jul 24, 2017
    Messages:
    742
    Location:
    Greenville Wisconsin
    Tire wear reduces diameter, and different tires will have slightly different diameters even at the same size.
    Tesla likely uses an average tire stat not a precise measurement of the original tires.

    The car and the phone are both likely rounding a bit, if they displayed a place after the decimal you might find them within .1.
     
    • Like x 1
  3. thegruf

    thegruf Active Member

    Joined:
    Mar 24, 2015
    Messages:
    1,832
    Location:
    UK
    @ratsbew you missed the /jk off the end of your post ;)
     
  4. Lasttoy

    Lasttoy Member

    Joined:
    Mar 24, 2017
    Messages:
    720
    Location:
    St Augustine, Fl
    My TomTom says same as my car. I checked it when i bought it. The police radars say the same.
     
    • Funny x 2
  5. TT97

    TT97 Active Member

    Joined:
    Aug 6, 2017
    Messages:
    1,251
    Location:
    Los Angeles
    I am assuming you have had your phone GPS recently calibrated and certified to be accurate.
     
  6. VT_EE

    VT_EE Member

    Joined:
    Apr 22, 2017
    Messages:
    480
    Location:
    Maryland
    If you are within 1mph of the true speed, you should be very happy. I have never owned a car that accurate (BMW, Toyota, Saturn, Mazda, etc).
     
  7. Thunder7ga

    Thunder7ga Member

    Joined:
    May 20, 2018
    Messages:
    160
    Location:
    Johns Creek, GA
    The town I live in has a few permanent speed indicator signs that show your speed and flash if you are 1 MPH over the limit. Based on what it (not very scientific by any means) says, the car indicates a speed about 1-2 MPH below what the sign typically says.
     
  8. ewoodrick

    ewoodrick Active Member

    Joined:
    Apr 13, 2018
    Messages:
    1,080
    Location:
    Buford, GA
    1%is well within the tolerance of 10%. 1% can easily be explained as rounding error.

    I suspect that your GPS manufacturer wouldn't say that it's device supports 1%
     
  9. Runebane

    Runebane Member

    Joined:
    Jul 12, 2018
    Messages:
    78
    Location:
    Visalia, CA
    I'm curious, does the Model 3 user GPS to determine speed or does it do it like other vehicles and it's the rotation of the tires? If the latter, most companies err on the side of caution. IE they set it so you think you're going faster than you are.

    Mine is 2 MPH faster than what I see with my phones GPS. That's 1 MPH better than the car I replaced, it was 3 higher than my phones GPS.
     
  10. aronth5

    aronth5 Long Time Follower

    Joined:
    May 8, 2010
    Messages:
    1,986
    Location:
    Boston Suburb
    I had the same thought.

    Trying to figure out if the OP's posting is serious or not since the only ratings on the initial posting are "funny".
     
  11. ratsbew

    ratsbew Member

    Joined:
    Mar 3, 2012
    Messages:
    717
    Of course I'm serious. I'd fully expect the speedometer to be dead on. Anything other than that isn't telling me the info that I want.

    It should be quite easy to periodically calibrate the speedometer with the GPS.

    As for my phone's GPS, it's true that I just picked up an app from the app store. I'd assume it to be correct, but I should probably use my cycling GPS that has speed to the tenth.
     
    • Disagree x 1
  12. AnarchyEOD

    AnarchyEOD Member

    Joined:
    May 23, 2018
    Messages:
    273
    Location:
    Magnolia, DE
    That’s it.. burn it to the ground!
     
  13. MRPLUGIN

    MRPLUGIN Member

    Joined:
    Jan 8, 2017
    Messages:
    84
    Location:
    Utah
    That's the final straw!....I'm canceling my reservation!.....OH I already have it.........What is this world coming to.
     
    • Funny x 2
  14. aronth5

    aronth5 Long Time Follower

    Joined:
    May 8, 2010
    Messages:
    1,986
    Location:
    Boston Suburb
    I have a Garmin Edge 800 and have compared my speed with a cyclist riding next to me. Our speeds typically vary and are more likely to differ then be the same. I'm not saying the Tesla speed is accurate but it isn't something I worry about.
     
  15. Runebane

    Runebane Member

    Joined:
    Jul 12, 2018
    Messages:
    78
    Location:
    Visalia, CA
    You do know that cars do NOT have an accurate speedometer right? Unless you pay a 3rd party to tune it to 100% it's going to be off and most likely reporting higher than what it really is.
     
  16. brkaus

    brkaus Active Member

    Joined:
    Jul 8, 2014
    Messages:
    4,380
    Location:
    Austin, TX
    It’s also common practice to report faster than actual. No blame for speeding tickets. My bmw, Acura, dodge, and Tesla are all off. The Tesla is closest.
     
  17. seyclone

    seyclone Member

    Joined:
    May 8, 2018
    Messages:
    82
    Location:
    NY
    Truly an Earth shattering first world problem.
     
    • Funny x 1
  18. MP3Mike

    MP3Mike Well-Known Member

    Joined:
    Feb 1, 2016
    Messages:
    6,849
    Location:
    Oregon
    By law a speedometer can never report slower than you are really moving, but they are allowed to report up to 5% faster than you are going. As a result all speedometers read faster than you are actually going.
     
  19. Jonathantuba

    Jonathantuba Member

    Joined:
    Dec 2, 2017
    Messages:
    58
    Location:
    UK
    Mercedes cars under-read by 3mph, so I would consider within 1mph pretty accurate. And it is the right side to stop you getting speeding ticket.

    The speedo on my model X seems spot on, going by readside displays of my speed
     
  20. widodh

    widodh Model S 85kWh

    Joined:
    Jan 23, 2011
    Messages:
    6,001
    Location:
    Middelburg, The Netherlands
    #20 widodh, Aug 13, 2018
    Last edited: Aug 13, 2018
    I am not sure about the US, but as far as I know in Europe there is a law that a Speedometer always has to be slightly inaccurate to make sure that people are never speeding by accident. This way they can't get a ticket if they stick to exactly the speed on their speedo.
     
    • Like x 1

Share This Page

  • About Us

    Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.
  • Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


    SUPPORT TMC