Which is accurate, HUD or Speedometer?
Driver
Joined: Nov 2012
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From: IL
One way the HUD would be "less accurate" than the mechanical speedometer: Put substandard processor in HUD circuitry, a comparator circuit that does not quite compare well. I know. I know. But if Lexus says the speedometer is the baseline device, then they designed the HUD a bit off. Doesn't make sense.
CL Community Team
Joined: Feb 2001
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From: Ohio
If they designed it to be a "bit off," then it is accurate as we are using the term. That readout would be relatively accurate (relative to design and to other instruments in the same car, as much as they also use the same design goal modifications) but not absolutely accurate (convening actual speed of the vehicle on the ground). I think we have been assuming that manufacturers were trying to give us a device that would give an accurate reading in absolute terms, so as to be both useful and so as to coordinate with devices in other (even state-owned) vehicles. If these devices of measurement are designed to be not accurate ("a bit off") then (a) what good are they, other than as cautionary devices at the third-grade level and (b) we are wasting our time here.
Last edited by tfischer; Dec 21, 2012 at 06:33 AM. Reason: Delete references to Mayan End of the World.
Thread Starter
The pursuit of F
Joined: Jul 2006
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From: Toronto, Canada
Got Answers from Lexus on HUD / Speedometer "Accuracy" - Sort Of
Just in. We now know the HUD and Speedometer instrumentation have DIFFERENT sources for their display of the vehicle's speed. Got the official word from Lexus today when I brought it in for servicing. See pic attached. (ignore part that also includes the '13 model's ability to lock the car which I'll post in my other thread).
Now the fundamental question still remains and one may never know (which I'll reword slightly to avoid ambiguity) - which instrument displays the speed that is CLOSER to the actual speed of the moving vehicle?
Lexus could not answer that. My gut says the HUD is less accurate now that I know its source is the GPS/Satellite. To avoid any speeding tickets, I'll rely with the one that reads the higher speed (i.e. speedometer in my case).
Now the fundamental question still remains and one may never know (which I'll reword slightly to avoid ambiguity) - which instrument displays the speed that is CLOSER to the actual speed of the moving vehicle?
Lexus could not answer that. My gut says the HUD is less accurate now that I know its source is the GPS/Satellite. To avoid any speeding tickets, I'll rely with the one that reads the higher speed (i.e. speedometer in my case).
CL Community Team
Joined: Feb 2001
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From: Ohio
Well, that is indeed news, and a bit surprising, but it accounts for the reports of conspicuously different displays in the two readouts.
Who would have guessed this setup?
Thanks for that information.
Who would have guessed this setup?
Thanks for that information.
Thread Starter
The pursuit of F
Joined: Jul 2006
Posts: 8,296
Likes: 303
From: Toronto, Canada
Getting to the bottom of this was my pleasure. I totally enjoyed researching this and posting the facts.
Last edited by corradoMR2; Dec 21, 2012 at 07:20 PM. Reason: .
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