How accurate is the speedometer
05-31-2005, 04:33 AM
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My Ride: 535D Sport, Silver Grey, Black leather, Media/Visibility Package, M rear spoiler
Still accelerating, I assume the limiter is not on the speedometer. If not where is it? Also how accurate is the speedo?
05-31-2005, 04:50 AM
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There is an error built in which is a percentage of the speed so the faster you go, the higher it reads.
I read somewhere that the error is about 1.73 percent but I have no way of verifying whether or not that is the correct percentage figure...
I read somewhere that the error is about 1.73 percent but I have no way of verifying whether or not that is the correct percentage figure...
05-31-2005, 05:20 AM
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The 1.73% might be the right number. When checking against a GPS, I can't get the car speedo to match closer than 2 MPH. Often I will set the cruise on Interstates at 79 (10% over + 2 mph error) with little worry of being ticketed.
05-31-2005, 05:21 AM
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Originally Posted by Rudy' date='May 31 2005, 06:50 AM
There is an error built in which is a percentage of the speed so the faster you go, the higher it reads.
I read somewhere that the error is about 1.73 percent but I have no way of verifying whether or not that is the correct percentage figure...
I read somewhere that the error is about 1.73 percent but I have no way of verifying whether or not that is the correct percentage figure...
[snapback]134719[/snapback]
Also BMW recommends u not go over 3% higher tire diameter due to speedo cal, but that can be calibrated also and is just a "recommendation". Makes me think their using at least 3%+.
05-31-2005, 06:53 AM
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When comparing the speedo with my GPS at 70-80mph on a straight piece of road then my speed-over-ground readout is always 1-to-2 mph lower than the speedometer reading.
Doing the same in the streets at around 30mph then the readouts are fairly even.
That's not a very scientific experiment I know, but it does seem to duplicate JDN's experience.
Andy
Doing the same in the streets at around 30mph then the readouts are fairly even.
That's not a very scientific experiment I know, but it does seem to duplicate JDN's experience.
Andy
05-31-2005, 07:25 AM
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Originally Posted by Flowerfred' date='May 31 2005, 09:06 AM
And I suppose the more the tyres wear, the more it's off.
[snapback]134737[/snapback]
05-31-2005, 07:28 AM
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My Ride: 2005 545i (SMG)
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Another issue to remember...
Police radar/laser both operate on the doppler effect. This means that unless they are directly in your lane of travel, they will read slower speeds than you are actually travelling.... because they will have to read offline a bit.
Police radar/laser both operate on the doppler effect. This means that unless they are directly in your lane of travel, they will read slower speeds than you are actually travelling.... because they will have to read offline a bit.
