European speedos with 6% "Error"

[p.dath]

In Europe, at least for cars, they have a rule that a car speedo can never read more than the actual speed it is travelling at.
So how do the car manufacturers handle this? They introduce a deliberate 6% error, and report the car is travelling faster than it is. For example, if it says you are travelling at 100km/h, you are actually doing 94km/h. It stands out a lot when you use a GPS.

Most European cars are affected by this, like BMWs.

In NZ we don't have any such rule, and typically we have used "average speed" speedos. So if your car (assuming it wasn't made in for for Europe) says you are doing 100km/h, you are (within a small +/- range).

What I'm trying to find out is what regulations NZ has with regard to speedo accuracy. I've had a good search, and just kind find it.
I'm sure we must have something that governs this.

Does does anyone know the regulation/rule/legislation that covers this, or better still, can give me a URL so I can read it myself?

[ghost]

I believe NZ is around 9% lower, must never be higher. Mine is 8 ks out, ie 92 wheel speed when 100 GPS speed. Funnily enough, cruise control wont engage unless the car is doing 100 kph or less, and this is GPS speed not off the speedo speed, if you manually increase cruise speed over 100 k's it will slowly shift it back down to 100 k's over time.

Jappa car too.

[vifferman]

In Europe, at least for cars, they have a rule that a car speedo can never read more than the actual speed it is travelling at.
This is twaddle. I think you meant "never read LESS than the actual speed".
I think you'll find that almost all speedos are designed so that they are optimistic - that is, they read slightly higher than the actual speed you're traveling at. The convention is that odometers are fairly accurate, but speedometers tend to err on the side of over-reporting your speed. This is probably so that no-one can then go back to the manufacturer and say, "I got a ticket - I had the speedo calibrated, and it's your fault because it under-reads by 5%!"

But regardless - we've had this thread already recently.

[Devil]

Before you run out of braincells to waste, it is very very rare to come across a car with an accurate speedo* regardless of it's country of origin.

They're all over the place, with varying accuracies between brands, even within Japan.
There is no flat percentage rule amongst carmakers.

(* calibrated speedo's obviously excepted).

Note: Many car mag tests now show actual speed at an indicated 100km/h

[Morcs]

Nothing stops you:

Fitting a speedohealer to your bike

Disconnecting/ignoring your speedo on your car and using GPS.

I have my speedohealer setup to account for 6% overread, and it is still 1kph out at around 50kph.

[nosebleed]

If you really do want to add to your library, give Robinson Instruments a call.
They're in Sale St. Ak.

They should be able to point you in the right direction

[Stirts]

Dammit, I got all excited for a minute. From the title I was thinking that 6% of the Surf Lifesavers would be showing their budgies in error!!

My Mazda 121 Bubble speedo is spot on according to the GPS.

[p.dath]

This is twaddle. I think you meant "never read LESS than the actual speed".
I think you'll find that almost all speedos are designed so that they are optimistic - that is, they read slightly higher than the actual


Before you run out of braincells to waste, it is very very rare to come across a car with an accurate speedo* regardless of it's country of origin.


Believe it or not, as I said, in Europe speedos for cars are regulated so that they can not return a reading which is greater than the actual speed you are travelling at.

The last Holden I had that was manufactured out of Australia and used an average speed approach (and was pretty much spot on).
We mostly have Holden's at work, and we have GPS units for all the cars, and I can say all of them are also spot on.

Maybe I've been spoiled by Holden for too long.

[Devil]

You're contradicting yourself.
You mean: "they can not return a reading which is less than the actual speed you are travelling at."

[steve_t]

Most car reviews I can remember reading generally say that when the speedo indicates 100km/h, the car is actually doing 94-97 km/h.
Not sure about bikes but I have a feeling the accuracy is even less. There's a speed indicating sign down the road from me. I'll have to ride past and check out the difference. The only problem is once you get over a certain speed, it stop saying your speed and says "SLOW DOWN" :girlfight:

[Morcs]

I know my import honda cage overreads quite a bit. 60kph on the speedo is about 54kph

[p.dath]

You're contradicting yourself.
You mean: "they can not return a reading which is less than the actual speed you are travelling at."

You are correct.

[NDORFN]

We've got an Audi that I'm pretty sure is bang on. Haven't tried GPS yet but it's always on the dot with those electronic signs showing your speed. It probably did have the 6% margin built in originally but putting 2 inch bigger rims on it must've evened it out. With all the aftermarket wheels people use these days, having some kind of manditory margin is pointless. I like the way there's a 9km margin for issuing speeding tickets though. Makes sense.

[Flatcap]

The speedo needle on my MG Midget flaps about like a P-fueled epileptic.

I wonder what tolerances Morris Group worked to in 1970...?

[Ixion]

The speedo needle on my MG Midget flaps about like a P-fueled epileptic.

I wonder what tolerances Morris Group worked to in 1970...?

Thumbnail plus a fag paper was standard for most things.

[slofox]

Subaru Lancaster Wagon: speedo reads +4%
Suzuki SV650S K7: speedo reads +7%

These are "as far as I can tell" figures. Which means checked against mobile speed carts (of doubtful accuracy themselves), coppers with laser guns, GPS etc. Over quite a long period of time.

I reckon on the bike as long as the speedo doesn't read more than 115, I am probably under 110...(I hope :crazy:)

[The Wop]

I don't wear Speedos. They seem a little silly really.

[Morcs]

an accurate speedo is handy when you want to ride as fast as you legally can.

on the open road, 100kph limit, you can sit at 110kph without getting a ticket
Of course if your speedo is out by say 7%, and you sit at 110, your actually going 102kph, so you can still legally go faster, this is why I love speedohealers :whistle: 110 is 110, when riding near the tolerance you want to know exactly how fast you are going.

[Coldrider]

an accurate speedo is handy when you want to ride as fast as you legally can.

on the open road, 100kph limit, you can sit at 110kph without getting a ticket
Of course if your speedo is out by say 7%, and you sit at 110, your actually going 102kph, so you can still legally go faster, this is why I love speedohealers :whistle: 110 is 110, when riding near the tolerance you want to know exactly how fast you are going.My experience is between 100 and 110kph the fuzz are not going to ping me, but they flash headlights and let it be known they are not happy chappies.

[vifferman]

My experience is that there seem to be a lot of paranoid drivers out there, who (a) implicitly believe in the accuracy of their speedometer, and (b) believe that if they exceed 100km/h, they will be convicted of murder. It's really bloody frustrating to be driving following someone who's traveling at 90-95km/h, seemingly convinced they're sitting on the speed limit.
Contrary to what the LTSA's roadside propaganda would have me believe, 100 IS a target for me. I aim to be doing no less than that at all times on the open road, if I can possibly help it, while not going fast enough to attract the attention of the Gummint Revenuers.

[Devil]

an accurate speedo is handy when you want to ride as fast as you legally can.

on the open road, 100kph limit, you can sit at 110kph without getting a ticket
Of course if your speedo is out by say 7%, and you sit at 110, your actually going 102kph, so you can still legally go faster, this is why I love speedohealers :whistle: 110 is 110, when riding near the tolerance you want to know exactly how fast you are going.

You're still bargaining on a cop not being an arsehole and doing you for anything over 100km/h which he is legally entitled to do.

I do the same of course, try and sit at an actual 109km/h everywhere but realise that yes, I could get a ticket for that.

[Morcs]

You're still bargaining on a cop not being an arsehole and doing you for anything over 100km/h which he is legally entitled to do.

I do the same of course, try and sit at an actual 109km/h everywhere but realise that yes, I could get a ticket for that.

I did put the arsehole cop factor into my post originally but took it out :2thumbsup

[Dave Lobster]

I wonder what tolerances Morris Group worked to in 1970...?

Worked?? :eek5:

[MisterD]

The speedo needle on my MG Midget flaps about like a P-fueled epileptic.

I wonder what tolerances Morris Group worked to in 1970...?

Probably also something to do with the fact that the only thing "damped" about that vehicle is the interior when you don't get the hood up quickly enough...

[NDORFN]

You're still bargaining on a cop not being an arsehole and doing you for anything over 100km/h which he is legally entitled to do.

I do the same of course, try and sit at an actual 109km/h everywhere but realise that yes, I could get a ticket for that.

Highway Patrol are complete arseholes, I don't dispute that, but I have never heard of anyone getting nicked for anything under 110.

[RDjase]

We've got an Audi that I'm pretty sure is bang on. Haven't tried GPS yet but it's always on the dot with those electronic signs showing your speed. It probably did have the 6% margin built in originally but putting 2 inch bigger rims on it must've evened it out. With all the aftermarket wheels people use these days, having some kind of manditory margin is pointless. I like the way there's a 9km margin for issuing speeding tickets though. Makes sense.

I dont trust the accuracy of there electronic speed signs, My 07 hilux is out 9kms . 59kms on my speedo is 50kms onn the sign. Then i drive past a school at 59kms on my speedo and get a ticket for 57kms(in school time )and get a ticket. I would like to find out were there calibraltion certs are displayed for them. Cops didnt give a rats arse and i just payed the ticket.

Beware the electronic signs lulling you into false security

[NDORFN]

I dont trust the accuracy of there electronic speed signs, My 07 hilux is out 9kms . 59kms on my speedo is 50kms onn the sign. Then i drive past a school at 59kms on my speedo and get a ticket for 57kms(in school time )and get a ticket. I would like to find out were there calibraltion certs are displayed for them. Cops didnt give a rats arse and i just payed the ticket.

Beware the electronic signs lulling you into false security

I go 40 tops past schools anyway.

[slofox]

I have never heard of anyone getting nicked for anything under 110.

I have. Seem to remember a post on here a couple of weeks ago - dude got done for 104 FFS!

[RDjase]

I go 40 tops past schools anyway.

they park 300 mtrs away from the school over the road from the park , and i got the ticket at 10 45.

At school start and finish times i am very cautous. Kids as we know are very impulsive and do silly things, well i know my son does and would hate anything to happen to him as any parent would

10 45am ticket is just revenue grabing, and its a high school too, not little kids

[NDORFN]

they park 300 mtrs away from the school over the road from the park , and i got the ticket at 10 45.

At school start and finish times i am very cautous. Kids as we know are very impulsive and do silly things, well i know my son does and would hate anything to happen to him as any parent would

10 45am ticket is just revenue grabing, and its a high school too, not little kids

That's entrapment in my books. Unfortunately my book is morally inspired and the law regarding traffic offenses financially inspired.

[NDORFN]

I have. Seem to remember a post on here a couple of weeks ago - dude got done for 104 FFS!

That's insane. I'd have to see it to believe it.

[steve_t]

they park 300 mtrs away from the school over the road from the park , and i got the ticket at 10 45.

At school start and finish times i am very cautous. Kids as we know are very impulsive and do silly things, well i know my son does and would hate anything to happen to him as any parent would

10 45am ticket is just revenue grabing, and its a high school too, not little kids

I thought the ticketing anyone above 55km/h in front of a school was only between 7:30am-9:30am Mon-Fri. Or is that only here in Hamiltron? Oh and after school too

[RDjase]

I thought the ticketing anyone above 55km/h in front of a school was only between 7:30am-9:30am Mon-Fri. Or is that only here in Hamiltron? Oh and after school too

I thought it was something like that but couldnt be bothered with letters and all the crap over a $30 ticket.

[boomer]

In Europe, at least for cars, they have a rule that a car speedo can never read more than the actual speed it is travelling at.


This rule you quote... can you point me to it...??!!


man i can't believe the sh ite you come out with :wacko:

[Hitcher]

On the occasions when it works, the Shiver's speedo reports a 6% error. I know this because I have a GPS fitted to the bike for the occasions when the speedo doesn't work. The odometer, on the other hand, is accurate to 0.1%. Given that the speedo and odo share the same components, one can safely assume that the error is deliberate.

On other occasions, the speedo is all over the place like a mad woman's breakfast (I've had 100km of Lotto numbers once, and an indicated top speed of 200kmh) or not working at all. In those cases the error varies a little from the more usual 6%.

Oh, and did I mention that I've been waiting since March for parts?

[p.dath]

This rule you quote... can you point me to it...??!!

man i can't believe the sh ite you come out with :wacko:

http://www.answers.com/topic/speedometer

"In many countries the legislated error in speedometer readings is ultimately governed by the United Nations Economic Commission for Europe (UNECE) Regulation 39[4] which covers those aspects of vehicle type approval which relate to speedometers."

I'm guessing you hadn't heard of this legislation before?

[p.dath]

http://www.answers.com/topic/speedometer

"In many countries the legislated error in speedometer readings is ultimately governed by the United Nations Economic Commission for Europe (UNECE) Regulation 39[4] which covers those aspects of vehicle type approval which relate to speedometers."

I'm guessing you hadn't heard of this legislation before?


And if you want to get super technical, refer to:
http://www.unece.org/trans/main/wp29/wp29regs/r039r1e.pdf
Section 5.3.
Which specifies this formula for the standard error:
0 ≤ (V1 - V2) ≤ 0.1 V2 + 4 km/h
But I'll let you read it. It's a tad complicated for me. But basically, at 100km/h it equates to a 6% error.

[Hitcher]

http://www.answers.com/topic/speedometer

"In many countries the legislated error in speedometer readings is ultimately governed by the United Nations Economic Commission for Europe (UNECE) Regulation 39[4] which covers those aspects of vehicle type approval which relate to speedometers."

That reference doesn't validate your previous statement. It just allows for a maximum error margin for speeds over 40kmh.

[davereid]

I have got a Holden ute, its got an analog and a digital speedo, and a trip computer.

They are all different.

At 103 on the analog speedo, the digital one says 100. But if I lock the cruise control on, after a minute or so the computer will tell me average speed is 96.

Computer is very close to GPS.

[boomer]

That reference doesn't validate your previous statement. It just allows for a maximum error margin for speeds over 40kmh.


Exactly; teh standards are quite clear in what they're set out to achieve and its not what you're saying/claiming..... And many countries does not a Europe make...

[road king]

our trucks at work are all isuzu's. one of them reads 100km/h when your doing 90km/h. and another one reads about 80km/h at 90.



and the cops have a tolerance of 5km/h

[boomer]

In Europe, at least for cars, they have a rule that a car speedo can never read more than the actual speed it is travelling at.
So how do the car manufacturers handle this? They introduce a deliberate 6% error, and report the car is travelling faster than it is. For example, if it says you are travelling at 100km/h, you are actually doing 94km/h. It stands out a lot when you use a GPS.

Most European cars are affected by this, like BMWs.

In NZ we don't have any such rule, and typically we have used "average speed" speedos. So if your car (assuming it wasn't made in for for Europe) says you are doing 100km/h, you are (within a small +/- range).

What I'm trying to find out is what regulations NZ has with regard to speedo accuracy. I've had a good search, and just kind find it.
I'm sure we must have something that governs this.

Does does anyone know the regulation/rule/legislation that covers this, or better still, can give me a URL so I can read it myself?

your math is all wrong...



The indicated speed must never be less than the actual speed, i.e. it should not be possible to inadvertently speed because of an incorrect speedometer reading.
The indicated speed must not be more than 110 percent of the true speed plus 4 km/h at specified test speeds. For example, at 80 km/h, the indicated speed must be no more than 92 km/h.


110% +4kmh on 100 is 114 so in ur example if ur travelling literally at 94kmh then ur speedo may show upto 107.4 kmh



and Nz probably dont have any such guidelines because they dont build cars....

[p.dath]

...
110% +4kmh on 100 is 114 so in ur example if ur travelling literally at 94kmh then ur speedo may show upto 107.4 kmh


Not quite. I think this is the way it works.

v1=100km/h (displayed speed - how fast you think you are going)
v2=88km/h (actual speed you are going, ignoring fraction)

The rulle requires v1-v2 (which equals 12km/h) to be less than 0.1v2+4 (which equals 12.8km/h). v1-v2 must also be above zero.

So if you were a manuafcturer and wanted to sit in the middle of that range, then the speed offset would be 12/2 - or 6km/h.

Which supports what I said, that when the speedo displays 100km/h the actual speed (as report by GPS) is 94km/h - or a 6km/h error. Bang smack in the middle.

Make sense?

[Sam I Am]

so how without a gps can i messure out if my speedo is out ?

[Hitcher]

Not quite. I think this is the way it works.

v1=100km/h (displayed speed - how fast you think you are going)
v2=88km/h (actual speed you are going, ignoring fraction)

The rulle requires v1-v2 (which equals 12km/h) to be less than 0.1v2+4 (which equals 12.8km/h). v1-v2 must also be above zero.

So if you were a manuafcturer and wanted to sit in the middle of that range, then the speed offset would be 12/2 - or 6km/h.

Which supports what I said, that when the speedo displays 100km/h the actual speed (as report by GPS) is 94km/h - or a 6km/h error. Bang smack in the middle.

Make sense?

Apart from the spelling, no. 94 plus 6% isn't 100. And it's "bang smack in the middle" of what?

[Ronin]

so how without a gps can i messure out if my speedo is out ?

Ride past a cop at a steady 150 indicated and see what the ticket says.

[Sam I Am]

Ride past a cop at a steady 150 indicated and see what the ticket says.

PMSL thanks for the advice.....

[Ronin]

PMSL thanks for the advice.....

No charge...... excludes gumment revenoo charges

[p.dath]

so how without a gps can i messure out if my speedo is out ?

Find someone else who has checked their speedo against a GPS, and then ride along side them when they are doing a set speed.

[p.dath]

Apart from the spelling, no. 94 plus 6% isn't 100. And it's "bang smack in the middle" of what?

Using the formula, the tolerable error range when your speedo says 100km/h would be 0 to 12 km/h. So if you were building a speedo, and wanted to play it safe, you'd probably use the middle of that range.

When I first made the post it was based on some info a BMW car dealer say to explain why the BMW's did not say 100km/h when the true speed was 100km/h. The dealer said it is a legal requirement to have a 6km/h error.

However, since reading the regulation myself it is clear that is not the exact case. An error range is allowed, as opposed to a specific value, and it it so happens that 6km/h happens to be the mean of that error range.

[boomer]

Using the formula, the tolerable error range when your speedo says 100km/h would be 0 to 12 km/h. So if you were building a speedo, and wanted to play it safe, you'd probably use the middle of that range.

When I first made the post it was based on some info a BMW car dealer say to explain why the BMW's did not say 100km/h when the true speed was 100km/h. The dealer said it is a legal requirement to have a 6km/h error.

However, since reading the regulation myself it is clear that is not the exact case. An error range is allowed, as opposed to a specific value, and it it so happens that 6km/h happens to be the mean of that error range.

so.... you should think before you quote 'fact' and my workings were correct!

[boomer]

Not quite. I think this is the way it works.

v1=100km/h (displayed speed - how fast you think you are going)
v2=88km/h (actual speed you are going, ignoring fraction)

The rulle requires v1-v2 (which equals 12km/h) to be less than 0.1v2+4 (which equals 12.8km/h). v1-v2 must also be above zero.

So if you were a manuafcturer and wanted to sit in the middle of that range, then the speed offset would be 12/2 - or 6km/h.

Which supports what I said, that when the speedo displays 100km/h the actual speed (as report by GPS) is 94km/h - or a 6km/h error. Bang smack in the middle.

Make sense?


dude i read teh web pages, that makes sense.. you're making the shit up as you go along...

may i suggest in future u make a claim and point straight to your reference material. That way it cant be lost in translation!

[sinned]

My experience is that there seem to be a lot of paranoid drivers out there, who (a) implicitly believe in the accuracy of their speedometer, and (b) believe that if they exceed 100km/h, they will be convicted of murder. It's really bloody frustrating to be driving following someone who's traveling at 90-95km/h, seemingly convinced they're sitting on the speed limit.

It is extremely frustrating when they sit in the fast lane beside another vehicle. This is not such a problem when on a bike but a real pain if in a cage. The Wellington motorways are full of slow drivers hogging the fast lane.

It wasn't until I bought a new Mazda3 that I worked out why many drivers sit on 40 - 45kph in the commute to work. The Mazda speedo is out by 6kph at all speeds. My other car, 98 Corolla, has a speedo that reads spot on.


You're still bargaining on a cop not being an arsehole and doing you for anything over 100km/h which he is legally entitled to do.
I do the same of course, try and sit at an actual 109km/h everywhere but realise that yes, I could get a ticket for that.

Cruising in the discretionary ticketing zone is risky. When I see a cop or the radar detector warns me there is one around I drop the speed to 100kph. It doesn't make sense to antagonize them.

[Badjelly]

Mrs Jelly & I went to the trouble of calibrating the odometer and speedometer of our 1989 Ford Telstar s/w (a marvellous vehicle for relaxed touring by the way) on one of those marked-out sections of the road they used to have. Odo was 5% optimistic and the speedo another 5% optimistic relative to the odo, making the speedo 10% optimistic. (Yes Hitcher, I know 1.05*1.05 does not = 1.10. I'm using a first order truncation of a binomial expansion here.)

Jap import Mazda Familia of the same vintage is much more accurate, only a few % over.

I'm pretty sure the Scorpio speedo reads a bit high too.

Our Massey Ferguson tractor doesn't have a speedo and on the quad bike the speedo needle fell off a couple of years ago, so I can't report results for those.

[NDORFN]

Mrs Jelly & I went to the trouble of calibrating the odometer and speedometer of our 1989 Ford Telstar s/w (a marvellous vehicle for relaxed touring by the way) on one of those marked-out sections of the road they used to have. Odo was 5% optimistic and the speedo another 5% optimistic relative to the odo, making the speedo 10% optimistic. (Yes Hitcher, I know 1.05*1.05 does not = 1.10. I'm using a first order approximation to a binomial expansion here.)

Jap import Mazda Familia of the same vintage is much more accurate, only a few % over.

I'm pretty sure the Scorpio speedo reads a bit high too.

Our Massey Ferguson tractor doesn't have a speedo and on the quad bike the speedo needle fell off a couple of years ago, so I can't report results for those.


I'm infinately more interested in how fast you Massey Ferguson tractor can go than the accuracy of it's speedo.

[smoky]

Thought the title was about Europeans wearing speedos

[YellowDog]

Speed is a relative illusion.

If your speedo says 120kph, whether you are doing 125 or 115 changes very little apart from the few minutes earlier later you will arrive at you destination
(after being stopped by the cops).

When I drove in the UK motorways, my speedo rarely stated less than 130kph. That was an acceptable speed in those days and you would not ever get pulled over. I now use the NZ motorways at 100 - 120kph and do not get stopped either.

Psychologically, 100kph apprars to be a higher number than 80mph (even though it is slower)

I understand that the Police unofficially accept that speedos may be upto 10% out and hence you don't get pulled at 109kph.

This may or may not be correct?

[Badjelly]

I'm infinately more interested in how fast you Massey Ferguson tractor can go than the accuracy of it's speedo.

Well, it's hard to know because it doesn't have a speedo, but ... I reckon she (sorry he, his name is Edward) can cruise at 30 km/h and might do 40 km/h flat out. Steering at these speeds is a bit dodgy though. There's a lot of slack around dead centre so you tend to travel in a series of straight lines that converge more or less around where you want to go.