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      10-26-2016, 07:30 PM   #1
Jetmart
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My Speedo is off

I Found When I Am Driving Above Posted Speeds I Get Past A Lot More Than I Should. I Finally Brought Several Gps Units And Confirmed That The Car Over Reads My Speed By 5 Km/hr. I Think This Is Significant. I Wonder If The Odometer Over Reads As Well Racking Up Higher Milage Than I Shoud Be.
I Have Stock Tire Size And Rims On The Car. What Could Cause This?
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      10-26-2016, 08:50 PM   #2
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If you're getting that indicated vs actual difference at freeway speeds I'd say it's normal. In Europe (or maybe just Germany specifically) there's an allowable speedometer error, but it's can't at all indicate high with big penalties if it does. So most German cars have intentionally optimistic speedometers. The odometer will be accurate though.

You can actually use the Carly app to make the speedometer accurate. The only downside is the little bug that shows where the cruise control is set will still move to the old inaccurate position so it'll look like the cruise control isn't hitting the set speed.
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      10-26-2016, 08:51 PM   #3
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iT iS nORMAL fOr tHE sPEEDOMETER tO rEAD 2-3 mILES pER hOUR oVER tHE aCTUAL sPEED. nO wORRIES.
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      11-01-2016, 07:57 PM   #4
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i will shorten the snobby service guy's response:
"it's that way. there's nothing wrong."
i'm going to change service centers.
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      11-03-2016, 09:58 AM   #5
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the difference is also incremental. the faster you go the more it is off. More like a percentage than an actual miles per hour. like when I'm doing 35 I'm actually doing 33. but when I'm doing 70 I'm really doing 65 etc. This topic has been discussed for years on BMWs
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      11-03-2016, 10:17 AM   #6
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It takes just a small difference in an aftermarket wheel/tire combo to close the gap between the speedo readings.

If the speedo didn't understate the speed to begin with, it would be too easy to go over speed due to variances in diameters of tires.

I don't know if that is the true reason but that is how I explain it to myself anyway
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      11-03-2016, 12:07 PM   #7
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Some variance is fine. You'll notice sometimes you would be rolling at 2-5 mph and the speedo still reads 0.
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