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Speedometer weirdness?

Discussion in 'Gen 5 Prius Main Forum' started by Will B, Oct 2, 2023.

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  1. rjparker

    rjparker Tu Humilde Sirviente

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    As stated, the vehicle speed accessed via obd2 is accurate. We have side of the road radar displays and gps devices to validate it. The combo meter’s odo and trip meters are also accurate.
     
    #21 rjparker, Oct 3, 2023
    Last edited: Oct 3, 2023
  2. Will B

    Will B Active Member

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    Again, fully understand and agree on all the reasons why the speed displayed is generally higher than actual speed. To me the weird thing is if you are going to fudge the speed for rounding and/or legal reasons, seems like you should be consistent about it, do it not just for the displayed speed but also for the cruise control and speed warning sign. Kind of like why book/TV/movies have continuity checkers, make sure you present consistent information.

    I'm used to the displayed speed bouncing around some due to changes in slope or something, but it settles down. I see that all the time on my other two Prii, but here it is consistently off for long periods of time on even flat roads.

    Like the golden rule for criminals/politicians: "If you are going to lie, lie consistently!" Other than the quote, let's not go down that rabbit hole! :)

    will
     
    #22 Will B, Oct 3, 2023
  3. Gokhan

    Gokhan Senior Member

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    Cruise control is different. You need to study control theory, which is a whole field of its own. No effort is made to bring the controlled speed to within 0.1 mph. It is more like within 1 mph. It is like the temperature control of your A/C—you don't expect the actual temperature to be identical to the set temperature.
     
    #23 Gokhan, Oct 3, 2023
  4. RRxing

    RRxing Senior Member

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    Agreed. It's going to read high regardless of whether it's a percentage or a fixed value. It may vary based on manufacturer as well. Time to move on...
     
    #24 RRxing, Oct 3, 2023
  5. fuzzy1

    fuzzy1 Senior Member

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    Do note that this UN document is primarily a European region market standard, though Japan, Australia, New Zealand, and South Africa have also signed on.

    No countries in North / Central / South America are listed as signatories. I believe the U.S. follows a separate SAE standard.
     
    #25 fuzzy1, Oct 3, 2023
    Last edited: Oct 3, 2023
  6. Sharol

    Sharol Member

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    Same on our '23 Hycam. I've noticed it in the hilly area between our town and the one where we do our serious shopping (about 100 miles). Then when we are coasting downhill, it will get 1 or 2 miles over the setting. It only happens in cruise mode, though. The speedometer indicates that when I am manually managing the accelerator, it doesn't fight with me (and my mileage isn't as good).
     
    #26 Sharol, Oct 4, 2023
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