2018 Prius IV Speedometer Setting

Discussion in 'Gen 4 Prius Main Forum' started by prius4driver, Jan 6, 2019.

  1. prius4driver

    prius4driver Junior Member

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    I just updated my 2010 Prius IV to the current model. I haven't been on the forum lately--really lurked here in 2009 when I got the first Prius but learned how to drive it with the forums help and it was a fantastic car--reliable, great mileage, etc. I remember a thread that the speedo was set 2 mph off the shown speed--is this still true? The 2010 was checked on the roadside monitors and it was only going 53 at 55 mph. Need to know on the new one so I don't get caught. Sorry if this is a repeat--I didn't find a search box on this re-organized format.
     
  2. sclevine

    sclevine Member

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    I'm not sure if the difference is 2 MPH, but yes, actual speed is definitely a bit slower than what you see on the speedometer. If I'm trying to go 65, I put the cruise control on 68.
     
  3. The Professor

    The Professor Active Member

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    Compare it to the speed on the Sat Nav. GPS speed above 20mph is much more accurate. Generally the speedometer speed will be a percentage out, rather than a specific static offset. In every car I've ever driven, it's been 10% high, including my 2017 Prius. So it reads 33 when I'm going 30 and 77 when I'm going 70.
     
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  4. booke02

    booke02 Active Member

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    I've checked mine with the GPS of my SatNav - my speedo over-reads by about 8%.
     
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  5. Mendel Leisk

    Mendel Leisk Sidewalk Supervisor

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    Don't get caught going under the speed limit? (n)


    How about this: if you want to go a certain speed, go by the speedometer. If you're in actuality going a couple of mph slower, where's the harm?
     
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  6. alanclarkeau

    alanclarkeau Senior Member

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    Mine reads 103km/hr when the GPS says 100; 83 when GPS says 80; 62 when GPS says 60.

    Every car will read like that - my previous FIESTA read 108 when only doing 100.
     
  7. Elektroingenieur

    Elektroingenieur Senior Member

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    Not always 2 mph, but the speedometer is still designed to read high. The Repair Manual (more info), under Meter/Gauge System: On-Vehicle Inspection, has a table showing the intended error:
    Code:
    TECHSTREAM INDICATION (MPH)  ACCEPTABLE RANGE (MPH)
                20                      20 to 22
                40                      40 to 42
                60                      61 to 63
                80                      81 to 83
               100                     102 to 104
               120                     122 to 124
               140                     143 to 145
               160                     163 to 165
               180                     184 to 186
    “Techstream Indication” is the highest speed measured by any of the wheel speed sensors, observed with the Data List feature of a Toyota Techstream diagnostic system, and “Acceptable Range” is the speedometer display. The table is repeated for km/h, but the numbers are the same.

    I’ve explained the relevant regulations in a previous thread.
     
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  8. Prodigyplace

    Prodigyplace Senior Member

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  9. prius4driver

    prius4driver Junior Member

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    Thanks, guys--pretty much the same as my 2010 I think. We have a straight stretch of highway (12 miles) into town and hardly anyone dries at the 55 mph speed--including the county Mounties who patrol this section. I just want to be able to keep it under 70. I haven't even opened the SATNAV manual yet--that is way over my head. It has been a steep learning curve for this old lady to learn how to drive the new one! Still haven't qiote mastered that cruise control--we keep the little manual in the front seat of the car to refer to. Just put my first tnk of gas in it--had to master the tanks and mileage first! A little off topic but how do you change info in your account? I found the sport, but when I use the sliding scale to add the 2018 it only goes to 2012. My trip computer mileage is about the same amount off of hand computed mileage--at least 2 mpg, but I am getting much better mileage on the new one, even with new Toyo tires on it. My Michelins with 50K miles were doing pretty good by mileage always down in the rain, cold and wind of Western Oregon winters I like having now to have to plug up half of my radiator every winter.
     
  10. prius4driver

    prius4driver Junior Member

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    Funny one on the slow driver--but sooooo dangerous! Is marijuana legal in Ontario?
     
    #10 prius4driver, Jan 6, 2019
    Last edited: Jan 7, 2019
  11. Prodigyplace

    Prodigyplace Senior Member

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    In Ontario Canada, apparently since last October it is.

    Cannabis legalization
     
  12. robsnyder20

    robsnyder20 Active Member

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    Yes, about 2MPH I noticed at 60MPH. Something sort of interesting that I noticed, On a flat level road (I live in FL), if you set the cruise say at 60MPH (so it shows you moving 60) it shows the average speed recorded by the car at 58 MPH. I have a 2016 with the 15 Toyos.
     
  13. alanclarkeau

    alanclarkeau Senior Member

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    I didn't realise a PRIUS would go at 180 MPH? 180 km/hr would have my licence suspended for many years here - and I think my car would be crushed - or maybe that's the 2nd time.

    That's pretty well what my 2 different GPS agrees with - in km/hr:
    upload_2019-1-7_12-57-28.png

    It can vary a bit with tyres which are worn - or flat.
     
  14. Mendel Leisk

    Mendel Leisk Sidewalk Supervisor

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    Don't conflate one with the other: over-reporting of mph is by legislation; over-reporting of mpg is just Toyota's ploy to cheer up drivers, gain them extra rosy reports from reviewers, stuff like that.

    "Fixing" the speedo, and the hypothesis that mph being off causes the mpg exaggeration, both these topics come along very frequently.
     
  15. alanclarkeau

    alanclarkeau Senior Member

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    Yes, true, ever car over-reports km/hr - by legislation it can't be under - so they err the other way, as if tyres are changed/flat/worn and can make them read slightly different.

    But - every car over-reports the l/100km - FORD did it on both mine, KIA did it too. Though, it can be a bit different for every fillup. My fill last time was about 8% optimistic which is typical (5-8%) - but this time, it was 11% back the other way - in other words, I actually got 11% better than the dashboard told me (79UK MPG). Different pump might have cut off at different time.
     
  16. Mendel Leisk

    Mendel Leisk Sidewalk Supervisor

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    Our previous Honda Civic Hybrid reported liter/100km either spot-on or slightly pessimistic, ie: if calculated was 5, it was display 5.0 or 5.1. Pretty much without fail.

    But yeah, apparently an outlier.

    Back to the "topic", and I used quotes because I'm somewhere between frustration and puzzlement: I can't understand why there's so much consternation regarding a slight over-reporting by the speedometer.

    I suspect it's tied to a generational thing: a couple of my kids that drive have told me, in all seriousness, that the speed limit is the lower threshold you should be driving. Sadly, they may be right, or at least in the majority.
     
    #16 Mendel Leisk, Jan 7, 2019
    Last edited: Jan 7, 2019
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  17. Prodigyplace

    Prodigyplace Senior Member

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    Many times here I see people regularly 10 mph over the limit.
     
    #17 Prodigyplace, Jan 7, 2019
    Last edited: Jan 7, 2019
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  18. Prodigyplace

    Prodigyplace Senior Member

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    You would not want to get a ticket in BC for driving too slow... :whistle:
     
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  19. Mendel Leisk

    Mendel Leisk Sidewalk Supervisor

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    Or for coming to a full stop at a stop sign. Ditto when turning right on a red light. Or observing speed limits through playground and school zones. :rolleyes:
     
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  20. Prodigyplace

    Prodigyplace Senior Member

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    So many cars must be out of blinker fluid too.
    Perhaps it is getting expensive & hard to locate so people ration it by rarely using their turn signals.
     
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