Your speed is...

[c00ky83]

I notice these things cropping up, where the sign says "Your speed is..." and then your speed flashes up in lights.  However, I passed one at 30 yesterday and it said "26".  Hmmm.  Next time I went at 30 according to the sign and my speedo said 35!  Who's right?

[Fitzer]

Most probably the sign, car speedos are notoriously inaccurate (the regs have recently been tightened though). My GPS regularly shows a slower speed than my speedo indicates (2001 Alfa 147), indicated 70mph shows as 65/66 on the GPS.  

Ian

PS. Don't go thinking that this means you can 'speed' according to your speedo as all manner of things can affect indicated speed :-)

[Cockney_si]

Not sure but it's a bit silly when they spend all these thousands on signs that tell drivers of their speed when you get cars that come with speedos from the factory.

Isn't that ironic....Don't you think.

[Hermia]

These sound a really bad idea! I was driving behind a car yesterday which nearly crashed because the driver was looking at a billboard. A sign which tells you your speed sounds really distracting!

[kempie]

UK law, actually EC Community Directive 75/443(97/39), requires speedometers to read between 0 and 10% fast, thus preventing the driver from inadvertantly exceeding any applicable maximum speed limits.

It appears that your speedo is over-reading by about 15% which is outside this tolerance.

I wonder who would be prosecuted for this offence?

[c00ky83]

For the record:  If I'm on a motorway going past a camera, I see cars either side of me doing exactly the same speed, so I think the signs are wrong!

[kempie]

The way to check your true speed is to place a GPS receiver on your dashboard.

[John Brennan]

ask a policeman

[Phileas]

I am new to this, and having just logged on, cant get back to acknowledge the contributors I refere to.

I used a GPS to confirm my speed over a few years and probably over 100,000 miles now.

I often found my speedo to be over-reading. HOWEVER, it was nearly allways spot on with new tyres.

My belief is that these warning signs are usually correct. I would rather see more of these than Speed camera's as they are active reminders and encourage forward looking rather than head down speedo concentration!