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After much suspicion, I have verified that the speedometer on my 2001 Boxter S (12,000 miles)

is reading consistantly 4 mph faster than the actual speed of the vehicle (stock wheels and tire sizes).

Are there any programming changes or calibration updates that can correct this?

Does anyone else have this concern?

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After much suspicion, I have verified that the speedometer on my 2001 Boxter S (12,000 miles)

is reading consistantly 4 mph faster than the actual speed of the vehicle (stock wheels and tire sizes).

Are there any programming changes or calibration updates that can correct this?

Does anyone else have this concern?

I also have an '01 Boxster S (with 102,400 miles!) and i was using a borrowed GPS the other day, and my speedo is also registering 4 mph fast.

I doubt that there is anything we can do, other than keep that 4 mph in the back of our minds. My Land Rover LR3 also registers 4 mph fast, can you say conspiricy? ;)

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All speedometers reed a certain % too higher/much, in speed and distance as well. There are company's which are able to calibrate the speedo/odo meters, ask the police where they go's.

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After much suspicion, I have verified that the speedometer on my 2001 Boxter S (12,000 miles)

is reading consistantly 4 mph faster than the actual speed of the vehicle (stock wheels and tire sizes).

Are there any programming changes or calibration updates that can correct this?

Does anyone else have this concern?

I found this same problem with my '97 tip, when I bought it last spring, posted the same question and found that there is nothing to be done. :(

I live with it and it drives me nuts! :blink:

You would think that this could be remedied with the advanced electronics on these cars today. :lightbulb:

It is a distracion having to calculate mentaly how fast you are really traveling. :drive:

The only thing is it might save you some money on tickets if you ignore the error. :clapping:

Paul

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Agreed with RFM, wvicary.

I was drving thru the school zone the other day, their indcator was 2miles slower than mine,,,,

im wondering how uguys are actually compaing your speed?

Do U ever come to think that theirs(laser,GPS) might be off, or get a new set ot tires (as they wear from 10/32 tread depth,odometer will read a bit faster)

But to make some of U happy- these guys can do it

http://www.tachosoft.com/pics/porscheboxster.htm

Edited by juniinc
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Can someone tell me why this problem is such a concern. It's only a few kph/mph over the actual speed..... what's the big deal??

We'll for some of us this concern is 4-6mph and not acceptable for quality car builders.

As a matter of fact Honda Ridgelines have a class action lawsuit on the matter for the same factor we experience.

"Odometer: Due to a class action suit claiming that the odometers were reading high, the company extended the mileage warranty by 5 percent. (2006)"

This has been well documented as a concern on this site and other by boxster owners.

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This is done on purpose due to a german law than places large fines on manufacturers that have speedometers that read too low. If you display the actual speed in the DME you will see that the speed is artificially increased in the speedo display over that determined by the wheel sensors. It does not affect the odometer readings as that would be illegal.

-Todd

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This is done on purpose due to a german law than places large fines on manufacturers that have speedometers that read too low. If you display the actual speed in the DME you will see that the speed is artificially increased in the speedo display over that determined by the wheel sensors. It does not affect the odometer readings as that would be illegal.

-Todd

I do not doubt your reason but never noted such a difference on my Audi or BMW!?!?

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Normally this error is not a problem but when you do a TSD (time speed distance) rally with any of the local clubs you are put at a disadvantage, you can not use your gps to correct your speed and have to figure it in constantly even though the odo may be correct, :unsure: I would see this as a safety issue as it distracts the driver. For a manufacturer to build this into cars is not acceptable and it is really sad. :(

Paul

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Hello everyone,

In Europe there is a regulation from the European Community Authorities that allows a positive deviation of the speedometer indication for all car manufacturers as follows :

Actual/real speed + 10% + 4 km/h.

This means that when the car is driven exactly at a speed of 100 km/h then the speedometer may indicate 114 km/h !!!

Also according to this regulation the speed indicated by the speedometer may NEVER be lower than the actual speed of the vehicle.

This means that when the car is driven at an exact speed of 100km/h then the speedometer may never indicate 99km/h or lower.

Of course not all car manufacturers do fully use the allowed positive deviation, but you will all know that there are no 2 identical parts in the world, clearances and deviations will always be used in mechanical or electronic parts.

I hope the concern is somewhat healed with this explanation.

Regards,

Alfred

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btw, I had been worrying about the idea of crash data recorders recording erroneous data and being used against you. Imagine that you're driving 55 in a 50mph zone and hit some kid that runs into the street. Now imagine if the CDR recorded you driving 62mph (10% + 4kph [stupid km]). This could make a big difference between minor speeding versus calling it "reckless" driving in a lawsuit, all due to a faulty speedo and stupid kid.

After doing some checking, I was relieved to discover that Porsche doesn't use crash data recorders, but a surprising number of companies are using them today.

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Also if you read above, you will see that the speed in the DME is accurate, it is altered only in the instrument display.

There are a number of electronic speedo correctors you can by that simply alter the speed signal to modulate the instrument display.

-Todd

btw, I had been worrying about the idea of crash data recorders recording erroneous data and being used against you. Imagine that you're driving 55 in a 50mph zone and hit some kid that runs into the street. Now imagine if the CDR recorded you driving 62mph (10% + 4kph [stupid km]). This could make a big difference between minor speeding versus calling it "reckless" driving in a lawsuit, all due to a faulty speedo and stupid kid.

After doing some checking, I was relieved to discover that Porsche doesn't use crash data recorders, but a surprising number of companies are using them today.

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  • 1 year later...

Hello,

I do not understand why this topic is such an issue for some people.

Even when using electronic speed correctors it will be necessary to (weekly, monthly, yearly???) recalibrate the speed corrector to compensate the wear of the tyres !

For a technician it is not difficult to understand that assembled units either if they are mechanical or electronic, have a technical tolerance.

With the standard speedometer in your Porsche you will never drive 55mph in a 50mph zone unless YOU want to do it . In that case your speedometer will always indicate that your speed is minimum 55mph.

I wonder what speed it will indicate when you 'use' an 'aftermarket' electronic speed corrector which is not regularly recalibrated !

Alfred

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I do not understand why this topic is such an issue for some people.

The reason I noticed it in the first place (before checking the accuracy) was that, on the motorway,

I was always holding people up. The speed limit is 65 and almost all traffic runs 72. You try to drive

the maximum speed without danger of a ticket and to keep traffic moving smoothly.

Now after the error revelation I am constantly mentally checking and recalculating so as to both

not get a ticket and not get run over at the same time.

Also, some small town speed traps in the U.S. will give you a ticket for 2-3 mph over the posted limit.

It's not the ticket (about $80.00) but the fact that after the most innocent ticket, your insurance will

go up about $100.00 per quarter for the next eight quarters (about $880.00 in total).

This is a pain in the brain, a pain in the wallet and a pain in the a$$.

There is no viable excuse.

Edited by 986fan
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My '99 Box is 4 mph off, the 2002 Pontiac Grand Am I owned before it had no deviation at all. There is a fix for it but the time and expense of removing the instrument cluster, shipping it, waiting for a week or more for calibration and the cost of the calibration are not cost effective. I agree it is a shame that a high performance sports car like Porsche has a speed variation but it really only becomes an issue when the law is involved.

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