Adjust speedometer

[leifnel]

This new Yaris hybrid reads the signs, and display a red sign in the display when it thinks you're speeding.

However, this speed shows around 5 km/h too much, so this warning is useless.

Can this error be corrected?

My dream is a GPS-speedometer automatically adjusting the traditional speedometer ratio, as GPS does not work in tunnels and urban canyons all the time, but is far more accurate than the traditional speedometer.

[FROSTYBALLS]

The TSS warnings are probably linked to the accuracy of the speedometer.

The in built optimism for a speedometer is due to international agreements covering accuracy - the UNECE regulation states that speedometers should never under read and that they should not read more than 110% plus 6kph

In the EU the requirement is slightly different - speedometers should not read more than 110% plus 4kph.

In the UK the requirement is again slightly different - 110% plus 6.25mph for speeds between 25 and 70mph.

Modifications, tyre wear, temperature, vehicle load, tyre pressures, etc may all affect the speedometer reading, so one will probably never get a totally accurate speedometer.

[leifnel]

Regardless that the -meter must lie when the car is sold.

Why can't a dealer or the customer adjust the speedometer later? 

Especially when the car alerts when the car is over the incorrect speed.

[Heidfirst]

5 hours ago, leifnel said:

Regardless that the -meter must lie when the car is sold.

Why can't a dealer or the customer adjust the speedometer later? 

because your car would no longere meet it's type certification  (which may mean that your insurance becomes null & void etc. etc.)...

I just learned to mentally adjust the indicated mph to "true". Does your car have satnav?

 

btw, do you need to adjust your profile?

[leifnel]

The car doesn't have satnav, as I see no reason for paying for a system which have few features, does not have daily updated maps, and will likely not get firmware updates after a few years.

I use Waze, in this way I also have a speedometer which does not intentionally lie to me.

[Bomber209]

If you had a built in 'Sat Nav' you would be able to set at what speed over the limit you want the warning to appear (so maybe a use after all). I regularly find that my speedo over reads anyway, compared to radar set speed limit warnings. This can vary with tyre wear as the tyre circumference reduces. 

[FROSTYBALLS]

On 03/09/2017 at 8:23 PM, leifnel said:

I use Waze, in this way I also have a speedometer which does not intentionally lie to me.

GPS uses a number of waypoints to produce an average speed, so although not 100% accurate, it is more accurate than vehicle speedometers.

Using either a sat nav or sat nav app is the most cost effective way to gain more accurate speed readings. t

There is no certain way to adjust one's speedometer to improve accuracy and remain road legal, given the number of variables which can affect speedometer readings (temperature, tyre wear, etc).