Incorrect Speedometer - Golf mkVII?

[AdamD]

You can also see it in the secret menu in an RNS510 in other models. Dont know if you can do that in the Mk 7

I don't believe you can. But either way, looking at your headunit to check speed isn't exactly safe.

[Hillbilly]

I don't believe you can. But either way, looking at your headunit to check speed isn't exactly safe.

I dont actually and only use it to occasionally calibrate the HUD so my eyes never leave the road. LOL

[DV52]

That's Paul, not Ryan.


There is a solution to this problem. Buy an Autopolar FIS+ (once the Mk7 firmware is released) or similar, that interfaces directly into the canbus and displays the real vehicle speed, without any error introduced. That's what I do, and the reported speed matches up precisely with my GPS devices I've used to verify it.

Paul: my apology for the error!
Adam: Yes, I'm looking forward to the mk7 release of the FIS+. Any idea when?

You can also see it in the secret menu in an RNS510 in other models. Dont know if you can do that in the Mk 7

What secret menu? How do you access this menu on the RNS510 and I will try on the Discover media unit?

[Hillbilly]

Paul: my apology for the error!
Adam: Yes, I'm looking forward to the mk7 release of the FIS+. Any idea when?



What secret menu? How do you access this menu on the RNS510 and I will try on the Discover media unit?

Kamold will have a better idea than I about it on a Mk7 but in the 510 you need the later firmware which we get off here and then hold down the setup button for about 20secs.

[Golf Girl]

Yep its pretty common for new or vaguely new cars to be under in their speedo. My Mk6 golf is under by 8kph (110kph is really 102kph). Was the same for my 2006 Hyundi Getz out by 5kph. Look at it as a safety feature. I suspect it's deliberately done by the manufactures now because we are to stupid to follow the road rules.

Just know your difference then you can adjust your cruise control to match. Set yours to say 115kph and you'll still be under the speed limit but closer.

[Hillbilly]

Yep its pretty common for new or vaguely new cars to be under in their speedo. My Mk6 golf is under by 8kph (110kph is really 102kph). Was the same for my 2006 Hyundi Getz out by 5kph. Look at it as a safety feature. I suspect it's deliberately done by the manufactures now because we are to stupid to follow the road rules.

Just know your difference then you can adjust your cruise control to match. Set yours to say 115kph and you'll still be under the speed limit but closer.

If you read through the thread you will see that it has nothing to do with manufacturers. It is an Australian Design Rule (ADR)
The rule basically reads that the speedo cannot read LESS than actual speed and can read over by up to 10%<>4.
Manufacturers have absolutely no say. They must comply with the Rule.
It is to allow for variations in tread wear and wheel sizes etc.

[NCGR1]

Dutch77: yes, that's true. But in the 21st century, I would have thought that we could rely on better metrics in our cars.....

Not sure what the century we are in has to do with it. There are numerous items, all with tolerances, that add up to determine the indicated speed in the cluster. How would you approach it but assure no vehicle sold to a customer indicated low? Calibrating each and every vehicle at the completion of build would certainly not be practical.

[DV52]

Not sure what the century we are in has to do with it. There are numerous items, all with tolerances, that add up to determine the indicated speed in the cluster. How would you approach it but assure no vehicle sold to a customer indicated low? Calibrating each and every vehicle at the completion of build would certainly not be practical.

NCGR1: Thanks for your thought provoking question, which I would like to answer by asking a few questions of my own (please don't read anything nefarious into my questions - they are simply intended to underscore my position).

What is the sole purpose of a speedo? Yes, it's a pretty fundamental question, but I believe that it's an important question in this issue. I hope that you will agree that the answer is to measure the car's speed!

What's the sole purpose of the road sign that has a number in a red circle (with a slash)? Again, very basic question but the answer is clearly to indicate the speed restriction - no doubt about this I hope!

IMO, when travelling on a freeway where the road sign says 110 Kms/hr- if it is better for the speed limit to be 95 kms/hr (i.e. 10% + 4 kms/hr slower), then this is what the road sign should say - and the speedo should accurately reflect the car's true speed.

I believe that when it comes to safety issues, mixing-up the two purposes above is wrong and just plain dangerous. Or, said differently, I believe that the "nanny" philosophy that compels car manufacturers to deliberately alter the speedo's reading is neither warranted, nor does it achieve a safer outcome.

You only have to look at what's happening on today's roads to find evidence regarding how under-reading speedos are affecting road safety, The inherent inaccuracy in the car's speedo is now well understood in the driving community. Commercial companies where business outcomes are link to time-on-the-road know that car speedos under read. Plus there is a good understanding of this practice amongst the wider community.

There are today readily available (and relatively cheap) ways of getting speedos with far greater accuracy (most of these are GPS based)

So, what we are increasingly seeing on our freeways is a two-speed driving phenomenon; those drivers that rely on their car's (under reading) speedos and those drivers that have chosen to use more accurate speedos. My view is that this is neither safer, nor it is a better outcome!

And it's not as if more accurate reading speedos are harder to get in 21st century cars. With the advent of OBD standards, most modern cars already record this data. For instance, the odometer on most cars in the 21st century already read to an accuracy of around 1%-2% (notwithstanding the ADR's 4% standard) -this level of accuracy probably results from litigation risk on warranty claims.

Distance travelled is of course a fundamental input to the measurement of speed and the car's speed as measured by the CAN bus is far more accurate than the speedo reading. So, in the 21st century, the car already measures speed far more accurately- it just doesn't display this speed on the speedo!

So, as a synopsis of my position, I think that it's far better, and it's proper to give the driver the very best available information for making decisions because ultimately there can be only one person responsible for the car's actions!

I'll get off my soap-box now and thanks again for your question.

[Hillbilly]

NCGR1: Thanks for your thought provoking question, which I would like to answer by asking a few questions of my own (please don't read anything nefarious into my questions - they are simply intended to underscore my position).

What is the sole purpose of a speedo? Yes, it's a pretty fundamental question, but I believe that it's an important question in this issue. I hope that you will agree that the answer is to measure the car's speed!

What's the sole purpose of the road sign that has a number in a red circle (with a slash)? Again, very basic question but the answer is clearly to indicate the speed restriction - no doubt about this I hope!

IMO, when travelling on a freeway where the road sign says 110 Kms/hr- if it is better for the speed limit to be 95 kms/hr (i.e. 10% + 4 kms/hr slower), then this is what the road sign should say - and the speedo should accurately reflect the car's true speed.

I believe that when it comes to safety issues, mixing-up the two purposes above is wrong and just plain dangerous. Or, said differently, I believe that the "nanny" philosophy that compels car manufacturers to deliberately alter the speedo's reading is neither warranted, nor does it achieve a safer outcome.

You only have to look at what's happening on today's roads to find evidence regarding how under-reading speedos are affecting road safety, The inherent inaccuracy in the car's speedo is now well understood in the driving community. Commercial companies where business outcomes are link to time-on-the-road know that car speedos under read. Plus there is a good understanding of this practice amongst the wider community.

There are today readily available (and relatively cheap) ways of getting speedos with far greater accuracy (most of these are GPS based)

So, what we are increasingly seeing on our freeways is a two-speed driving phenomenon; those drivers that rely on their car's (under reading) speedos and those drivers that have chosen to use more accurate speedos. My view is that this is neither safer, nor it is a better outcome!

And it's not as if more accurate reading speedos are harder to get in 21st century cars. With the advent of OBD standards, most modern cars already record this data. For instance, the odometer on most cars in the 21st century already read to an accuracy of around 1%-2% (notwithstanding the ADR's 4% standard) -this level of accuracy probably results from litigation risk on warranty claims.

Distance travelled is of course a fundamental input to the measurement of speed and the car's speed as measured by the CAN bus is far more accurate than the speedo reading. So, in the 21st century, the car already measures speed far more accurately- it just doesn't display this speed on the speedo!

So, as a synopsis of my position, I think that it's far better, and it's proper to give the driver the very best available information for making decisions because ultimately there can be only one person responsible for the car's actions!

I'll get off my soap-box now and thanks again for your question.

Your argument falls down at the first hurdle because not all cars have canbus.

[brad]

I do wonder if the bigger issue isn't so much our (crap) speedos or our crap laws that say our speed limit is a limit & you'll be punished if you exceed it.

eg: In Australia on a 2 lane motorway you'll often get Joe Blow in his Jetta driving along at the front of the queue in the RH lane. Beside him is a truck which is speed limited to 100. Joe Blow thinks the truck is being naughty because Joe's speedo says 110kph when in fact Joe is only doing 101kph. Joe is a law abiding citizen and wants to retain his right to travel at the speed limit and overtake so Joe just sits there with a 1kph variation between him & the truck beside him while the traffic banks up behind him & Joe gets angrier & angrier because those folks who have a speedo that is only reading 4kph under (the minimum allowable variation under the ADR) are getting more and more frustrated.

Of course, in Europe, the UK & the USA (I've driven in all three and seen how people drive) they don't seem to be as hung up about speed limits & Joe Bloe would give the throttle a squirt & move over. People overseas don't seem to take as much offence at being told to get out of the way.

BTW: I still claim the odometer is wrong too (about 3%-5%), therefore many people are getting their 15k service done at about 14250-14500km. It's not much but over 10 years....