Speedo Inaccurate

[Treza360]

Should be able to be corrected slightly with VAG-Com
Threads here: http://www.vwwatercooled.org.au/newf...ad.php?t=22508
and here: http://www.vwwatercooled.org.au/newf...ad.php?t=21307
with further links inside the last one. I imagine there will be some changes in the procedure and settings for the MkV and MkVI but nothing too dramatic.
Cheers,
Trent

[Zeke]

Basically at the speed of light as indicated on your speedo and factoring in the the 7% overread you would be approx 4 months late for your appointment at Alpha Centauri.

Equates to 1/100 of a Nano second late to your local Woolworths/Coles not factoring in delays at red lights.

4months late at Alpha Centauri assumes there are no traffic lights between Earth and Alpha Centauri

[Umai Naa!!]

^^ Nice one!

Basically, VW regards their speedos as accurate. As long as they're within the ADRs guidlines, they wont do anything about it.

[hoi polloi]

^^ Nice one!

Basically, VW regards their speedos as accurate. As long as they're within the ADRs guidlines, they wont do anything about it.

Although Australia is not a member of the ECE (Economic Commission for Europe) they are a signatory of their agreement for the harmonisation of vehicle certification standards. A lot of countries (like the US and Canada) are not... This is good for us as it makes it easy for European manufacturers (like VW) to certify cars for sale here as there is (I understand) reciprocal certification...

Beacuse of this, the speedo error that in the old days was ±10% does not apply to current models...

Be grateful for the fantastic choice we have in new cars bearing in mind we are a small market...

The certification requirements for speedometers are here -

http://www.unece.org/trans/main/wp29...gs/r039r1e.pdf

and largely repeated here -

http://rvcs-prodweb.dot.gov.au/files/ADR%201803.pdf

From this it appears that a speedometer cannot under read but can over read by 10% + 4km/h (para. 5.3)

Regards,
- Anthony.

[Deano]

i hav a copy of a bulletin from VW about customer complaints on incorrect speedo's, i will try and find it and post it up. IMO the GPS unit will be more incorrect than the speedo.

[Topend]

I have 3 mobile GPS units and they are all within 0.3km/h of each other. I also have had various boats over the years fitted with GPS plotters. They are also within 0.3km/h of my original mobile GPS unit.

Based on my experience my money is on the GPS being quite accurate.

[gregozedobe]

Based on my experience my money is on the GPS being quite accurate.

That is the general consensus, ie the analogue speedo is usually much less accurate than most GPS'. The OEM digital speed reading (if you can access it on your particular car) is usually pretty good, as is the MFD average speed.

[Corey_R]

That is the general consensus, ie the analogue speedo is usually much less accurate than most GPS'. The OEM digital speed reading (if you can access it on your particular car) is usually pretty good, as is the MFD average speed.

Yeah - the digital speedo is usually accurate. I'm surprised the OP is saying that it's only 2km more accurate - which means it's still 5km too slow... that's strange.

[mtaoz3]

There are of course only two things required to measure speed: distance and time. We can assume that the clocks in our cars are accurate to within a few seconds a year, and the distance is from the odometer. The odo in my Mk VI is very accurate; 100.6km indicated = 100 km actual, which is of course a 0.6% error. Why the speedo error then? VW take the accurate figure, then deliberately multiply it by 1.06 and then display it. How do I know that? BMW do exactly the same. I once drove down the Hume to Melbourne and just before hitting suburbia I noticed that the distance computer said 300.0km, the elapsed time was 3h00m, and the average speed shown was...106km/h. Made me laugh that I had bought a $70k calculator that couldn't do a simple division accurately.

[prise]

Same problem with Mazdas I've owned. However the local product these days (ford, commodore) have speedos that are only optimistic by 1 km/h which catches a few people out when they rent them.

It would be very simple for manufacturers to have speedo calibration available on a menu in the MFD - its all SW controlled these days.