Engine weight 103 TDI

[Maverick]

Yep agree with both posts, will check whether distance travelled is more accurate than indicated speed.
I always found that Toyotas were spot on with speed. I have owned two corollas and a vienta and found that unlike the most Europeans they indicated speed pretty accurately.

They can't do this anymore. UNECE 39/00 (rev 1) which is used in most countries including Australia (ADR 18/03) does not allow the speedo to be accurate.

Volkswagen Speedometer Error Correction

[V6Passat]

Exactly our experience in the Golf too. Quick calc of 118 at 110 is 7%

Must be pretty common over a wide range of makes as sitting on 118 indicated you tend to catch and pass a lot of good citizens driving at their 110 indicated speeds.

Only seem to be passed frequently by red p platers at this speed.

My V6 Passt is the same. 7% difference between GPS and Speedo...then you put cruise on and the speedo says its 2% faster than the speed that the CC is set at.

[prise]

I borrowed a mates analyser to plug into the OBDII port and it was interesting to see that the cars speed as reported over the CAN bus was spot on with the GPS but the digital display was 6% optimistic and the analogue speedo was 7% optimistic. The car knows the correct speed as it should with oem tyres but as Maverick points out with his references they need to provide some margin on what is shown to the driver to cover different tyre fitments, etc. They would be in a lot of trouble if the speedo under read. The 6% however seems excessive given Holden can achieve 2% with their locally produced cars.

[Corey_R]

It's obvious that the car knows exactly what speed that it's doing, but that VW have chosen to put the 7% over-read in there.
I think that maybe there are some more specific rules in the EU or something, because several other Euro brand cars I've been in are also 7% or very close to...

[Cossor]

It's obvious that the car knows exactly what speed that it's doing, but that VW have chosen to put the 7% over-read in there.
I think that maybe there are some more specific rules in the EU or something, because several other Euro brand cars I've been in are also 7% or very close to...

So without Sat nav, are the speed check radars used in Vic on Hume H'Way accurate? Eg, use to calculate
an offset for when setting cruise control? (With commodore around 4K diff at 110KPH, Corolla spot on)

[Corey_R]

I don't trust those "side of road" speed check displays... they're often wildly inaccurate.
But if you don't have a GPS device, you can do the "trip meter reset trick". Change to the "average speed" display on your trip meter, ensure you're doing the speed you wish to calculate (i.e. a steady 100kph as indicated on your speedo), and then reset the trip metre. The first number that appears in the average speed is the REAL speed you are doing (well... as long as you're still on the standard tyres and wheels and therefore haven't introduced any inaccuracies).

This works on pretty much all VW's.
So if you're going 100kph, you reset the trip meter and the average speed appears as 93kph, you know that you too have the 7% over-read.

[Idle]

So without Sat nav, are the speed check radars used in Vic on Hume H'Way accurate? Eg, use to calculate
an offset for when setting cruise control? (With commodore around 4K diff at 110KPH, Corolla spot on)

I've run under both those and the newer ones on the Prince's Freeway near Geelong — both gave me the same reading (92K at a speedo-indicated 100) so I'd say they're pretty close.

To stay with the bulk of traffic in a 100-limit area I have to run just under 110 on the Mk6 TDI speedo — I'm slowly getting used to it, but after a couple of decades with a car that read pretty much spot-on, I still feel a bit nervous.

Whilst I can understand the thinking behind such a built-in error, I still think it's stupid.

Mentally calculating the difference helps take the driver's concentration off what he/she should be doing, which is attending to the already complex business of driving.

And to those who say that driving at the speedo indicated pace is safer, try doing it in traffic — you'll very soon tire of being tailgated and abused.