Speedo Mph Or Satellite Mph

[YarisOAP]

When doing 70 mph on the speedo the Satellite says 67 mph which is right or more reliable

[Jan&tone]

you will probably find that neither are 100 percent accurate best thing is those roadside 'your speed is' signs and you will most likely find that your speedo is 2mph faster than those signs say you are doing...

Bear in mind that satnavs are only accurate to within 20 yards so even that will be slightly out on your speed!

[edtwozeronine]

Doing 34mph on my speedo those signs tell me I'm doing 31mph. So to be legal I should do 33mph I assume...

[Madasafish]

It is a legal requirement in the UK for all speedometers to read fast - 5% if I recall.

So an indicated 70mph is a real 66.5mph. Or less.

[Geoff Peace]

It is a legal requirement in the UK for all speedometers to read fast - 5% if I recall.

So an indicated 70mph is a real 66.5mph. Or less.

No legal requrement to read 'fast' only that they must not read 'slow' Modern electronic speedometers are much more accurate than the cable driven ones. Main reason for reading slightly fast is to accommodate the difference in circumference between a new tyre and one at the legal limit. Depending on tyre size the difference is around 2.5%.

Regards Geoff Peace.

[liam6200]

for speeding fine reasons too, if it was 100% acurate and you drifted over 30mph slightly going through a camera in a 30mph then it might trigger it where if its slightly out and you drift over then ul be still within the 30mph limit :D

[guynecologist]

The speedo in my T-Sport over reads.

Checked it against my Sat Nav and when 70 on the speedo it was about 65 on the Sat Nav.

What I also did was repeat the speedo check, but instead against the digital trip meter.

The T-Sport trip meter has 3 modes Current MPG. Average MPG, and Average MPH. The second 2 modes listed if you hold the button in, it will beep and reset to 0 MPG or 0 MPH, then after a couple of hundred yards update to show a new average MPG or average MPH.

So on a flat straight bit of motorway late in the eve, sat the Yaris at 70 mph on the speedo holding it there, pressed the reset for the average mph, drove a couple of hundred yards then glanced at the new average MPH which was about 65 same as the Sat Nav.

[acetip]

In 5th gear my auris 1.6 should be doing 20 mph for each 1000 revs. If i drive at 3000 rpm the speedo indicates about 65 mph.which a simuler difference others have found when comparing satnav readouts to speedo ones.i thnk i can safely assume my rev counter is pretty accurate,but the speedo is not.