Speedo Accuracy - which one is correct.

[EuroBro]

I have my tomtom GPS on which shows the current travelling speed via satelite updating every second which was 7 kms/hr slower than the 100km/hr in-dash speedo reading.

I reckon honda has sped-up the needle to protect the service & warranty (7% is a huge margin)! :confused:

[TypeG]

my tomtom appear to be the same as my speedo

[EuroDude]

Yes the GPS is more accurate than the Euro's speedo, but its probably 1 or 2km/h off.

Car manufacturers rarely calibrate the correct speed, one reason is for safety. The Euro's typically go about 96km/h when the speedo shows 100km/h.

When I drove past one of those "you are going XXkm/h, SLOW DOWN!" road construction signs, it showed 63km/h when the speedo showed 68 or 69km/h

[mr_mojo02]

also depends on ur gps. some will update quicker than others

[aaronng]

Wheels tested both the base and luxury Euro 1 year apart and found that the actual speed was 96km/h when the speedo was indicating 100km/h.

[TypeG]

must be something wrong with my car then coz i am surprise how accurate my GPS is
haha

[MiSloVic]

the euro's speedo with 225/45R17 is quite accurate.. i've tried the radar speed detector along the melbourne end of Hume highway, set the cruise control at abt 100km/h and the speed indicated by the radar is 100km/h.

however.. when i tried the one along Geelong, at 100km/h, there is a difference of 4km/h.

[btchia]

the euro's speedo with 225/45R17 is quite accurate.. i've tried the radar speed detector along the melbourne end of Hume highway, set the cruise control at abt 100km/h and the speed indicated by the radar is 100km/h.

however.. when i tried the one along Geelong, at 100km/h, there is a difference of 4km/h.

my euro with 225/45R17 is different detect on the albury to Melbourne radar speed detector, cruise at 120km/hr, radar indicated shown only 114km/hr, so not sure which is correct.....

[EuroAccord13]

The other factor is that the speed is read as a digital and it has to convert to analog for the needle (This creates a 2-4% error)..

The needle reads 100km/h but my RSM reads 97Km/h

For those who has the RSM in the car, you'll see that the RSM speed is actually spot on and can be confirmed by driving through the speed radar... I know my RSM is accurate :)..

[EuroBro]

I just repeated my test and can confirm it is 96kms/h @ 100 - but still 4km/h adds up to 400kms/1000kms service intervals and a whopping 4,000k's more when I sell it @ 100,000k's.

[ZEi20T]

dont forget those radars are also badly calibrated and MAY tell you a faster speed to get you to slow down

[EuroBro]

dont forget those radars are also badly calibrated and MAY tell you a faster speed to get you to slow down

That's an excellent point - better to be safe than sorry. I reckon you could have a convincing case if you can prove that your speedo is slower using a GPS receiver.

[yfin]

I just repeated my test and can confirm it is 96kms/h @ 100 - but still 4km/h adds up to 400kms/1000kms service intervals and a whopping 4,000k's more when I sell it @ 100,000k's.

If you look at the car magazines that test the speedo with VBOX or whatever sat device they use - many cars are like this from many different manufacturers.

So it is not as if it is some conspiracy by Honda to change the service interval, or the odomoter of your car.

For a few hundred bucks you can get the RSM as explained above and set the speedo correction at whatever you want. I use it mostly for the speed alarm function as well as having some curious fascination for electronic speedos. Must be something to do with Knight Rider from my childhood.

[aaronng]

I just repeated my test and can confirm it is 96kms/h @ 100 - but still 4km/h adds up to 400kms/1000kms service intervals and a whopping 4,000k's more when I sell it @ 100,000k's.
You'll find that the error comes from converting the digital signal to analog for the speedo. The odometer is still digital and shouldn't have that error.

[Mr_will]

another point worth noting is that adr states that all speedos must be accurate +/- 10% above 40km/h, meaning that if you complained to honda, they would probably just tell you that they complied with adr and thats all they really have to do

[ZEi20T]

there is a very good way of testing your speedo. chuck it on a dyno! test LEGALLY at whatever speeds you want :)

[EuroDude]

cop cars are calibrated properly, next time you see a cop, drive beside them at the same speed and roll down the window and ask them what speed they are going lol

[ZEi20T]

just so you are all aware. GPS is NOT a good way of measuring/testing speeds. remember the resolution of a consumer GPS is ~10m. think of 10m when you are travelling 100km/h. it might think you are either 10m behind or infront and its never consistent no matter how many sats you have in sight.

only the military has GPS resolution of like 0.0005mm :P

[PNR888]

circumference of your tyres (new vs worn, different sizes etc). Smaller the circumference, higher the speedo reading.
So if you dont want to clock up your unnecassary kilometers, dont wear worn tyres, get largest possible tyre size (in terms of circumference, within legal limit of course) and make sure the tyres are properly inflated

[Chris_F]

ROGER!

I was about to start a thread to make sure you were still alive haha..

[yfin]

just so you are all aware. GPS is NOT a good way of measuring/testing speeds. remember the resolution of a consumer GPS is ~10m. think of 10m when you are travelling 100km/h. it might think you are either 10m behind or infront and its never consistent no matter how many sats you have in sight.

only the military has GPS resolution of like 0.0005mm :P

But if you are cruising at a steady speed, on flat ground with good sat lock the GPS should be deadly accurate - eg set the cruise at 100km/h. There could be a lag initially but if you are at a steady speed you can check the speedo that way.

[tanalasta]

Quite a number of vehicles have an accurate speedo at lower speeds but at 100km/h become slightly 'low'. If you look at wheels reports, a number of cars show 100km/h when the car is actually travelling 93-96km/h.

Saves you getting a speeding ticket I suppose :p Mine does the same.

[tony1234]

Quite a number of vehicles have an accurate speedo at lower speeds but at 100km/h become slightly 'low'. If you look at wheels reports, a number of cars show 100km/h when the car is actually travelling 93-96km/h.

Saves you getting a speeding ticket I suppose :p Mine does the same.
Yeah. I think when Wheels(or Motor)tested the Euro they stated the speedo error at 100ks was like 3% reading 97ks i think!!!:)

[EuroBro]

If you look at the car magazines that test the speedo with VBOX or whatever sat device they use - many cars are like this from many different manufacturers.

So it is not as if it is some conspiracy by Honda to change the service interval, or the odomoter of your car.

For a few hundred bucks you can get the RSM as explained above and set the speedo correction at whatever you want. I use it mostly for the speed alarm function as well as having some curious fascination for electronic speedos. Must be something to do with Knight Rider from my childhood.

Thanks for that, what you said makes the most sense- Although I can't help you with your electronic speedo fetish - you can blame KIT for that!:)

[Suntzu]

My GPS is very accurate as far as i can tell. With my 18x7 wheels Im indicating 98kph and the gps is 100kph. I always use the gps and it has reduced my traveling times due to the fact that im EXACTLY on the speed limit not under it.

[Adagio]

Don't forget any reading you get from a GPS is historic as it is an accumulated reading from up to 9 satellites and all this takes time. The more or less satellites your GPS is able to receive at any given time affects the accuracy of the information it is giving you. I agree that, not just Honda, most cars are about 4-5kph out at an indicated 120kph so that you are really only doing about 116kph the lower the speed the closer the difference is between your GPS and your car's speedo.
Adagio

[ZEi20T]

Don't forget any reading you get from a GPS is historic as it is an accumulated reading from up to 9 satellites and all this takes time. The more or less satellites your GPS is able to receive at any given time affects the accuracy of the information it is giving you.

if anyone has watched the raw data from a GPS they would see this occurring.

someone mentioned the Apexi RSM before, that wheel size adjustment option is awesome!

[Omotesando]

the euro's speedo with 225/45R17 is quite accurate.. i've tried the radar speed detector along the melbourne end of Hume highway, set the cruise control at abt 100km/h and the speed indicated by the radar is 100km/h.

however.. when i tried the one along Geelong, at 100km/h, there is a difference of 4km/h.

Interesting because, when I try my 225/45R17 equipped Euro on the Hume Hwy just a bit past Thomas Town where speed limit is 110kph, probably the same one that you checked with, I'm doing 112kph cruise control on Speedo - the sign says I'm doing 106kph.

That's why Steve Bracks is an IDIOT with the 3kph limit. Speedos or thos radar speed detectors aren't even that accurate... :(

[tony1234]

Interesting because, when I try my 225/45R17 equipped Euro on the Hume Hwy just a bit past Thomas Town where speed limit is 110kph, probably the same one that you checked with, I'm doing 112kph cruise control on Speedo - the sign says I'm doing 106kph.

That's why Steve Bracks is an IDIOT with the 3kph limit. Speedos or thos radar speed detectors aren't even that accurate... :(
I'm glad we haven't got that 3kph limit.How can you have such a low tolerance?You're right Bracks is a f^*hwit.

[EuroDude]

What is the limit in Sydney?

[tony1234]

What is the limit in Sydney?
I've heard 10%???Don't quote me though!:zip:

[MiSloVic]

Interesting because, when I try my 225/45R17 equipped Euro on the Hume Hwy just a bit past Thomas Town where speed limit is 110kph, probably the same one that you checked with, I'm doing 112kph cruise control on Speedo - the sign says I'm doing 106kph.

That's why Steve Bracks is an IDIOT with the 3kph limit. Speedos or thos radar speed detectors aren't even that accurate... :(

hmm.. is your tyres getting bald? actually, word on the streets are that this margin is more than the claimed 3kph..

[blk05gli]

navman ICN720 shows 96 when I'm on cruise at 100 on dial.

[tony1234]

3-4 kph.less seems to be the built in tolerance when your'e doing 100 kph.

[Cranial]

I've just put on some new wheels and tyres, 225/40 18". I just went cruising at 110kmph steady according to my GPS, but the speedo reads ~130kmph. Is there something really screwed up here?

[minircc]

eurobro, when you sell it the meter will be to your advantage.. ie. you will have travelled 100,000kms but speedo will show less not more.

tyre size and wear also has an impact on the speedo.
remember the only thing giving you the readout from the dash is the diameter of your wheels.