Speedometer Discrepancy

[gnr3312]

I use Waze for all my navigation purposes and it has a built-in speedometer which we find useful at times. I come from a Defender and it always matched the speed of that vehicle, and on my son’s Subaru as well. However I have noticed that the speed on the Taycan’s screen is showing up 3 miles over what Waze says I’m driving at. Has anyone seen this before? I have stock 21” spyder tires on a 2024 4S.

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[Tooney]

Speedometer Error
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[gnr3312]

Speedometer Error
Search is your friend.

Thank you! I did a search for driving speed difference but not speedometer.

 

[DerekS]

You know, every Porsche I’ve ever had seems exactly 3mph over.

 

[69Mach390]

Speedometer Error
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That thread, nor this thread answer the question though:

Is it off by 3mph or by 6%?

Would it be off by 6 mph at 100 mph or still 3?

Either way, this is the “most wrong” I’ve seen a car from the factory.

 

[JayMo35]

Mine is actually shows 3 mph slower than what Waze says and when you pass those speed limit signs that show your speeds.

 

[Fogsvans]

I don't know if there is a difference between the US and Europe but in general the speedometer is showing more than the actual speed. In the old days with analoge meters running with wire between a wheel and the meter, the difference was always a percentage of the actual speed but with the electronic meter of today manufacturers usually program it to show X kmh/mph more than the actual input from the wheel. This is also depending on the size of the tires where 5% difference more or less circumference from the standard is accepted but not more.

 

[KLHubb]

I was under the impression that Porsche speedo's over state the speed by a bit, just to be conservative and give you a bit of leeway when exposed to radar.

 

[anonymouse]

I was under the impression that Porsche speedo's over state the speed by a bit, just to be conservative and give you a bit of leeway when exposed to radar.

In Europe, it's due to regulation: under EC/ECE Regulation 75/443/EEC and more recent approvals, when tested at 40, 80 and 120 km/h and all speeds between them:

• A speedometer may read up to approximately 10% above the true speed plus 4 km/h
• It must never be below the actual speed.

The manufacturer will be refused type approval for the vehicle if they exceed these bounds. Or they could be fined €30,000 per noncompliant vehicle.

In the UK this tolerance in speedometers and in measurement devices correlates to the general practice by police (per guidance from the National Police Chiefs' Council) of allowing 10% + 2mph over the speed limit in practice before imposing fines -- although they can prosecute for 1mph over if they want to.

 

[KLHubb]

Thanks.,very sensible.

 

[Horizontally Opposed]

I use Waze for all my navigation purposes and it has a built-in speedometer which we find useful at times. I come from a Defender and it always matched the speed of that vehicle, and on my son’s Subaru as well. However I have noticed that the speed on the Taycan’s screen is showing up 3 miles over what Waze says I’m driving at. Has anyone seen this before? I have stock 21” spyder tires on a 2024 4S.

I use Waze and ignore the speedo.

 

[gnr3312]

I use Waze and ignore the speedo.

Which one do you ignore, Waze’s or Porsche’s?

 

[69Mach390]

Which one do you ignore, Waze’s or Porsche’s?

If we’re being honest, likely the speed limit.

 

[Mr.Smith]

3mph inaccurate, even over 100mph

 

[kern417]

Have the same "issue" on all of my german cars. I'd say it's pretty common on multiple makes, but it's a % increase.

Is there a way to code it out? on BMWs it's a checkbox that you can disable, although if you ever change your wheel/tire diameter then it can throw it off again.

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