[Rolebama]

I am curious. Has anyone here ever compared their GPS to speedo reading?
Mine hasn't got a speed readout, but it does warn me if I go even one mph over both the posted speed and the max speeds I have set for different road types. (ie motorways, major A roads, etc).

[Drivingforfun]

I had a 2002 Mini Cooper, it only had a speedo in the centre of the dashboard, not one behind the steering wheel, so I bought a GPS speedo to stick where the speedo would go in most other cars. They were very very close in speed readout.

One thing I have noticed with my current car is that when I go past those signs that tell you how fast you're going, my speedo always seems to be 1-2 mph over what the sign reads out.

[Santa]

Originally Posted by Drivingforfun

One thing I have noticed with my current car is that when I go past those signs that tell you how fast you're going, my speedo always seems to be 1-2 mph over what the sign reads out.

I have noticed the same thing. I think that they are deliberately set low for some reason.

[Beelzebub]

Originally Posted by Santa

I have noticed the same thing. I think that they are deliberately set low for some reason.

They don't need to be, since speedos are deliberately set high ...

[NMNeil]

It's unlawful for a manufacturer to have the speedo show less than the actual road speed.
This was originally intended to overcome the inherent inaccuracy of a mechanical speedometer, also to allow for tyre wear which will change the recorded speed; gear ratios and all that.
https://hansard.parliament.uk/lords/...ometerAccuracy

[Beelzebub]

Originally Posted by NMNeil

It's unlawful for a manufacturer to have the speedo show less than the actual road speed.
This was originally intended to overcome the inherent inaccuracy of a mechanical speedometer, also to allow for tyre wear which will change the recorded speed; gear ratios and all that.
https://hansard.parliament.uk/lords/...ometerAccuracy

That is true, but after the manufacturer has sold the vehicle the responsibility passes to the driver to ensure the speedo is "maintained in good working order.".

[NMNeil]

Originally Posted by Beelzebub

That is true, but after the manufacturer has sold the vehicle the responsibility passes to the driver to ensure the speedo is "maintained in good working order.".

As far as I'm aware all speedos and mileage counters are digital and due to people clocking odometers they are a sealed unit to avoid tampering with the mileage. So a touch difficult to ensure they are in good working order.
I suppose you could remove the speedo and send it back to the factory so they can check it for accuracy, but how many times have you done that with a car you own?

[Beelzebub]

Originally Posted by NMNeil

As far as I'm aware all speedos and mileage counters are digital and due to people clocking odometers they are a sealed unit to avoid tampering with the mileage. So a touch difficult to ensure they are in good working order.
I suppose you could remove the speedo and send it back to the factory so they can check it for accuracy, but how many times have you done that with a car you own?

They may be physically sealed, but the software is accessible, at least if the companies offering "mileage correction are to be believed.

[NMNeil]

Companies openly advertise clocking?
Amazing

[Rolebama]

I , as well as friends have used these services. My instrument cluster failed and I bought a new one. I had the original mileage set to my new speedometer. (Some cars carry the mileage reading in the ECU so it is automatically reset.) My friends in the motor trade have fitted second-hand clusters and have had mileages reset to original mileages. (Most customers in this situation ask for reduced mileages, but they are told that they are quite at liberty to arrange this themselves.)