BMW Speedometer question...

BLWN DSG

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So a friend i work with just bought a new BMW and was told something very concerning to me...

He was told by a technician that BMW speedometers are calibrated from the factory to run 2.5mph slower than the actual speed. Meaning you can set the cruise control to 60mph but a GPS device will show you going 57.5mph. But the odometer is calibrated to read the actual mileage. I know it sounds confusing but this just seems weird to me why from the factory you would program it to be off....

Is there any truth that you guys know of to this?
 

xenodragon

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I wondered why when i passed those police speed signs it alway read lower than i thought i was going....could be true...not sure I care though.
 

BLWN DSG

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I wondered why when i passed those police speed signs it alway read lower than i thought i was going....could be true...not sure I care though.

Friend tested it with his Garmin and his phone both said the same thing. Why would they do it is my question? How can you sell a car and not tell them when you buy it...they are saying it is an actual percentage meaning if you are doing 80 according to speedo you are actually going 71 or so...
 

Torch10th

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Yes, they do in fact do this. DMW knows their demographic and they are simply looking out for them. By indicating a slightly slower speed (it's actually a percentage so it ramps) they are saving their customers money in traffic fines and insurance costs.

This is more of a big deal in Europe where those costs are far greater than we have here. BMW just carries over the programming to the states because it's cheaper to do so.

The Corvette's indicated speed is higher than actual by about 2mph and most German cars follow this same rationale. I know my GTI indicates 2mph fast at 30 and about 4mph fast at 75.

The 335XI I owned years back was about 4mph fast at 70.
 

thomas91169

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So a friend i work with just bought a new BMW and was told something very concerning to me...

He was told by a technician that BMW speedometers are calibrated from the factory to run 2.5mph slower than the actual speed. Meaning you can set the cruise control to 60mph but a GPS device will show you going 57.5mph. But the odometer is calibrated to read the actual mileage. I know it sounds confusing but this just seems weird to me why from the factory you would program it to be off....

Is there any truth that you guys know of to this?

Isnt this actually 2.5mph faster......

if they were calibrated slower, they would read 60mph when the car was doing 62.5mph.


Id like to know what factory calibration makes it to where all BMW douchebags have to drive 5-10mph faster than everyone else? The freeway could be doing 85 and always some doucher in a M needs to go 90-95.
 

04svtterm

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i have heard of this but never really tested it. I know i had an older 745 way back, where the speedometer was off but i'm pretty sure it was because of the aftermarket wheels.
 

BlueSnake01

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Yes they do. Same thing with my 335i. Saw a thread a while back on E90post about this.
 

BLWN DSG

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Thanks for all the replies. I was not aware that many car manufactures do that. I could see a small percentage due to tolerances but that large is interesting.

How does that effect the odometer? I ready the OBD is showing correct speed from one guys post so does that mean the odometer will be ok or will that be slightly off?
 

key

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The odometer is pretty darn close in my case.

I was surprised though when I booted up TestDrive (app I wrote) on my phone and saw the difference though..
 

286rocks

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My Mustang speedo reads a tad low too, Also any newer F-150s I've driven have also been a little below what GPS's and road signs read. I don't mind, it's probably saved me a ticket at one point or another.

If you want a super accurate speed just put the dash in "diagnostic mode".
 

SVT_4_me

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it's definitely true, but it's more like 5%. in my M3, at 75 mph on my speedo i am actually doing about 70 according to GPS.
 

99GTvert

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I think most car makers do this to some extent. I remember reading that they get fined themselves if they underrate the speed, so they give all cars a little wiggle room just to be safe.
 

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