Why different time estimates by Prius nav system and Tom Tom GPS?

Discussion in 'Gen 3 Prius Technical Discussion' started by Robert Holt, Apr 24, 2014.

  1. Robert Holt

    Robert Holt Senior Member

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    The in dash nav system on my 2012 level 3 Prius hatchback gives time estimates that are higher by about 10% than my Tom Tom GPS unit mounted on the dash. The Tom Tom unit appears to use the legal speed limits for the entire route for its time estimate. In contrast, the Prius nav system appears to use some estimate of average speed that depends on how close to the speed limit I am currently driving. The more slowly I drive, the longer the time estimates from the Prius nav system.
    Have others experienced this?
    Does anyone know the exact algorithm used by the Prius nav system to estimate time to destination?
    Thanks in advance.
     
    #1 Robert Holt, Apr 24, 2014
  2. kenoarto

    kenoarto Senior Member

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    TomTom has shortcuts and live traffic info. Prius takes major streets/highways only. One is an optimist the other is a pessimist!
     
    #2 kenoarto, Apr 24, 2014
  3. 70AARCUDA

    70AARCUDA Active Member

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    Tom-Tom unit is assuming legal posted speed (optimistic)?

    The Prius is assuming actual average speed that you've currently driven (realistic)?
     
    #3 70AARCUDA, Apr 25, 2014
  4. jdk2

    jdk2 Active Member

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    Does your nav unit in the Prius allow you to set speeds for rural, highway and city? Mine does but that may be model specific.
     
    #4 jdk2, Apr 26, 2014
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  5. Tideland Prius

    Tideland Prius Moderator of the North
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    You can set the speed limits on the Prius' nav under the Settings --> Navigation menu (menu layout may differ depending on Display Audio unit).

    TomTom uses speed limit info built into the map's database while Toyota's map is based on 3 types of road - residential, main street and freeway and you have to set the speed yourself.
     
    #5 Tideland Prius, Apr 26, 2014
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