[Jashue]

Last night coming home from a long trip I noticed that there is a discrepancy between all three means of checking my speed.
Set in cruise control at 75mph the GPS speed as indicated by Waze running on an iPhone 13 consistently showed 73mph. The speed indicated on my Escort radar detector showed a consistent 74mph. I find myself wondering if this is an isolated thing or if we all have speedometers that are off. Or could it be that the two GPS indicators are wrong?

Furthermore-- I'm wondering if the odometer is also wrong.

Does anyone have similar observations?

[ryo-]

my speedometer is roughly 1-2 MPH higher from my GPS on my radar detector. also, I noticed the same when you pass those radar speed tracker signs.

[zipstic]

Originally Posted by Jashue

Last night coming home from a long trip I noticed that there is a discrepancy between all three means of checking my speed.
Set in cruise control at 75mph the GPS speed as indicated by Waze running on an iPhone 13 consistently showed 73mph. The speed indicated on my Escort radar detector showed a consistent 74mph. I find myself wondering if this is an isolated thing or if we all have speedometers that are off. Or could it be that the two GPS indicators are wrong?

Furthermore-- I'm wondering if the odometer is also wrong.

Does anyone have similar observations?

This is possibly the most common question asked on this forum. The speedo is set to read around 3% to 3 mph higher than your actual speed. Auto manufacturers, especially in Europe, can be legally liable if the the speedometer indicators a slower speed than you're traveling, so they intentionally set it to show slightly faster than you're traveling.

And yes, your odometer is accurate.

[Winrya]

Originally Posted by zipstic

This is possibly the most common question asked on this forum. The speedo is set to read around 3% to 3 mph higher than your actual speed. Auto manufacturers, especially in Europe, can be legally liable if the the speedometer indicators a slower speed than you're traveling, so they intentionally set it to show slightly faster than you're traveling.

And yes, your odometer is accurate.

As above. Friend had a Nissan Nevara and its speedo was fast by 10%. This was within the up to 10% acceptable over read for the uk when he took it to Nissan. I had a golf Gti which was around 3% out and with vag.com you could program the driver side climate screen to show the actual speed the car was travelling which was gps accurate and the speed it uses to record accurate distance.

[RockCrusher]

Originally Posted by zipstic

This is possibly the most common question asked on this forum. The speedo is set to read around 3% to 3 mph higher than your actual speed. Auto manufacturers, especially in Europe, can be legally liable if the the speedometer indicators a slower speed than you're traveling, so they intentionally set it to show slightly faster than you're traveling.

And yes, your odometer is accurate.

That is my understanding and my experience.

My 230i's speedo reads between 1 to 2mph high. My M-B van likewise.

Other cars' speedos had errors ranging from none to 5mph high.

As for the odometer, years ago -- in 2002 -- when I bought my Porsche Boxster I noticed the speedo was reading 5mph high. I was concerned about the odometer. I set the trip odometer to 0 and my GPS device's distance to 0 then headed west -- pretty much driving as straight as an arrow flies -- across a portion of Kansas. At 200 miles showing in the GPS device the car's odometer read 200.2 miles. With a 50K mile warranty the 0.2 mile error over 200 miles works out to 50 miles error.

[danallxt]

my speedometer is roughly 1-2 MPH higher from my GPS on my radar detector. also, I noticed the same when you pass those radar speed tracker signs.

Same here, but my 2017 GTI was exactlly dead on right.

In the US by federal LAW speedometers can be HIGHER or LOWER than actual speed. So that excludes the liability excuse, as far as US anyway.

re: 49cfr393.82

§ 393.82 Speedometer.

Each bus, truck, and truck-tractor must be equipped with a speedometer indicating vehicle speed in miles per hour and/or kilometers per hour. The speedometer must be accurate to within plus or minus 8 km/hr (5 mph) at a speed of 80 km/hr (50 mph).

[70 FR 48054, Aug. 15, 2005]

[oldbmwtech]

Originally Posted by danallxt

Same here, but my 2017 GTI was exactlly dead on right.

In the US by federal LAW speedometers can be HIGHER or LOWER than actual speed. So that excludes the liability excuse, as far as US anyway.

re: 49cfr393.82

Mine reads faster too. Manufactures do this to end the warranty sooner than the max mileage, saves them a ton of money. Years ago I read an attorney sued over this.

[TJZ67201]

Originally Posted by oldbmwtech

Mine reads faster too. Manufactures do this to end the warranty sooner than the max mileage, saves them a ton of money. Years ago I read an attorney sued over this.

This is false. Already mentioned in this thread… speedometer may read incorrectly but mileage is reported correctly

This is well known with BMWs and as you can imagine, it's been discussed in millions of threads on this forum

[RockCrusher]

Originally Posted by oldbmwtech

Mine reads faster too. Manufactures do this to end the warranty sooner than the max mileage, saves them a ton of money. Years ago I read an attorney sued over this.

I don't think so...

The engine controller/instrument cluster controller record mileage. This is obtainable with the right diagnostics tool. Even if the speedo/odometer stop reading right at least the mileage is being recorded.

Way way back with another car I noticed the odometer was not counting the miles as it should. Speedo was working ok. Took the car in to the dealer. The car was tested and I was told since the speedo was reading right the car was ok.

Some few years later at another dealer for something else I learned there was a known problem with the model/year of car I owned. The grease used to lube the gear drive that moved the number wheels would dry out and the extra drag would keep the number wheels from turning. There was a recall on this. But the car was long out of warranty and I didn't care enough to bother having this done and having to pay out of pocket for it. IIRC the recall was no longer available for free.

And I recall a problem with a recent make/model of car in which the odometer would just stop counting miles at some goofy number like 13,342. Software bug...

In this case I think if this was deliberate on the part of the auto maker it got this wrong, it screwed itself. If only the odometer was available for mileage the car's warranty would never expire on *miles*.