Ridiculous Speedometer Error and On Purpose !!!

[brad]

Where did you do 160kph legally to check it

I don't know about him but I've regularly done 160kph on a racetrack.

I also have access to hundreds of kilometres of private roads where I've done up to 190kph.

[Eaglen00b]

*SNIP*Japanese cars stick around the 5km/hr mark in general. *SNIP*

I can confirm that. My old 1995 75 series troopy reads 5km/h over right through the speed range. The speedo is at 5km/h even when stationary. I know the speedometer is probably buggered but it still reads consistently 5km/h over even at 110kmh actual GPS verified speed.

[Eaglen00b]

Where did you do 160kph legally to check it

Oh I misspoke. I meant to say IF I were to go 160kph GPS speed.....

[feenix74]

I assume he drove it to NT and used the no speed limit area

[Guest001]

Oh I misspoke. I meant to say IF I were to go 160kph GPS speed.....

LOL......

[gldgti]

I could say I have done 160km/h but noone would believe me because all my cars are slow diesels.

[theresanothersteve]

Interestingly an ELM327 device plugged into the OBDII port through DashCommand gives the same speed readout as my GPS. The dash (both needle and digital display), however, is about 5% optimistic. So the ECU knows how fast you are really going.

The VE Commodores I've owned were always 2 kilometres an hour faster, irrespective of how fast you were going.

[LukePolo]

My polo seems to stick exactly 5km/h over from 0-130km/h

I had a VR commonwhore a couple years back, that was bang on the money.

[themarvel2004]

Isn't one of the main reasons for this so that if you go for a larger wheel/tyre combo, the increased rolling diameter doesn't result in your speedo under-reporting (ie showing less than actual)? Otherwise you would need to get it recalibrated every time you change wheel sizes, which would be a hassle given the options you can get from factory.
The good part is - if you fit larger wheels any time down the track it is still ok!

I just use my GPS speed to confirm actual speed vs indicated on the speedo and all is good.
Have been doing this for the past 15 years - not sure why it is such a new revelation for people...

[Guest001]

Isn't one of the main reasons for this so that if you go for a larger wheel/tyre combo, the increased rolling diameter doesn't result in your speedo under-reporting (ie showing less than actual)? Otherwise you would need to get it recalibrated every time you change wheel sizes, which would be a hassle given the options you can get from factory.
The good part is - if you fit larger wheels any time down the track it is still ok!

I just use my GPS speed to confirm actual speed vs indicated on the speedo and all is good.
Have been doing this for the past 15 years - not sure why it is such a new revelation for people...

The main and probably only reason is to comply with ADR rules. The recommended tyre sizes are on the placard and if you go outside that you are on your own. As well there are State rules as to how larger you can go with wheel & tyre sizes. Most will keep your speedo legal but some may not. Up to you to comply

[themarvel2004]

The main and probably only reason is to comply with ADR rules. The recommended tyre sizes are on the placard and if you go outside that you are on your own. As well there are State rules as to how larger you can go with wheel & tyre sizes. Most will keep your speedo legal but some may not. Up to you to comply

Not my point. To maintain/guarantee compliance with the ADR they are extra generous to ensure there are no problems with FACTORY wheel combos - as they would all have differing diameters and it would be a hassle to recalibrate every car of the probation line.

Realistically they only need to allow about 3-5kph variation and would still meet ADR, but all manufactures seen to chose to go more like 5-7kph.

[Guest001]

Not my point. To maintain/guarantee compliance with the ADR they are extra generous to ensure there are no problems with FACTORY wheel combos - as they would all have differing diameters and it would be a hassle to recalibrate every car of the probation line.

Realistically they only need to allow about 3-5kph variation and would still meet ADR, but all manufactures seen to chose to go more like 5-7kph.

Isnt that the same as what I said They have to allow for the largest size they specify for the model WORLDWIDE. In all cars the allowable sizes are on the tyre placard. They only have to allow for those.

If you choose to go larger well its up to you Some makes, as in my Toyota were dead on at 100kph so I couldnt put larger tyres on and be legal. Not Toyotas problem vehicle was legal as supplied.

The amount of variation differs between models as well. My two are not the same.

They probably use a production line but some of the workers may be on probation.

[stefcio007]

My Golf does 100km/h when speedo shows exactly 105km/h, all other times I just do the speed it shows on the speedo without adjusting because realistically only when you are doing long trips where you would be on the freeway would it matter. When I do exactly 100km/h I overtake a lot of people on the freeway so maybe newer cars are out by more.
Either way, this saves you when you accidentally go over the limit for a moment for whatever reason as I think you need to be doing something like 6km/h over to get booked. 6km/h alleged and then 3km/h over fined. (correct me if I'm wrong). With a speedo that is out you would need to be doing maybe something like 10km/h over to get a fine which realistically you won't do accidentally.

[EggsBenny]

Our VWs read 6.5% over, and the mrs' German-built Fiesta is more like 8% over. It pisses me off. They're perfectly accurate, while being out. No excuse. So I'm forever overtaking modern cars doing 93KM/H on the freeway.

I 100% use the digital gauge. Needle is too small an area, and also-out... So I'd rather lock cruise on 106KM/H, and have an audible warning for 107KM/H.

[Guest001]

The problem I see with this somewhat patronising factory speedo calibration is that the result is two distinct speeds adhered to by law abiding drivers... This amounts to up to 10km/hr difference in highway speed. Speed difference is not desirable from a road safety perspective and leads to mind bending frustration of those trying to do GPS speed behind someone doing speedo speed, especially when they're in the right hand lane...

Just stick to what the needle says and try not to get manic about it.