Speedo under reading?

[dsimpkins]

My local council have put up speed awareness signs on various roads near me recently. I've noticed that the speed the sign says I'm doing is 2 mph higher than the speed displayed on the dashboard. I thought speedos aren't allowed to under read, and that at speeds lower than 30 mph tend to over read.

So is my speedo working correctly, or are the council signs calibrated to read high? (possibly to get drivers to slow down more) Maybe I should test with GPS app on phone? In which case, any recommendations?

 

[Torryhun]

My gps & car speed always read the same, and the majority of time match road light up signs.

 

[JonnyG]

Same here - GPS speed from SatNav at 70mph almost spot on with speedometer.

 

[AlunJ]

Strange, has to be one of the most accurate speedos I’ve ever had, certainly it’s bang on with GPS anyway.

 

[dsimpkins]

Given the feedback I suspect the councils signs are over reading deliberately to get drivers to slow down. I will double check with GPS to be sure.

 

[Matt x power]

Mines bang on too

 

[Diggsy]

The council signs will be reading high to keep people below the limit. Don’t forget it’s a limit, not a target…and best to be driving below rather than over it anyway.

If your speedo is anything like mine it will be remarkably accurate. Mine reads the same as Google Maps

 

[Bricktop X PWR]

As above, Bang on.

I have to pass 3, yes three, active speed signs on the way out of Whitland, and at both 20mph and 30mph, they tally with my speedo.

I do 30mph when there is no one in front of me.

Let me tell you 30mph feels soo fast!
And to think that that, was the norm.

The 20mph scheme has definitely worked because as a rule I sit at 25mph.

Breaking the law, sure, but last year it may well have been 35mph.

(Steps into flameproof suit)

((Oh and I have the GPS speed readout on my dashcam))

 

[dsimpkins]

The council signs will be reading high to keep people below the limit. Don’t forget it’s a limit, not a target…and best to be driving below rather than over it anyway.

If your speedo is anything like mine it will be remarkably accurate. Mine reads the same as Google Maps

I'm under the limit, but the signs say I'm going faster than I am which I find annoying. I suspected the council signs were reading high.

 

[bedsev]

Mine is bang on too, most accurate I've ever had.

 

[Ian Key]

There's one of those signs near me but because the road is downhill and the sign is vertical it only picks vehicles up when they are almost on top of it and out of the drivers usual sight line.

Great for letting the cars behind know that the twonk in front is speeding as they merrily go on their way.

 

[OriginalBigAl]

My previous car used to under read by around 5kph, so my brain got used to the perception that 90 kph was the norm , whereas it was a true 85 kph . Now 90 kph does seem a lot faster even though its a more accurate reading legally its still a little disconcerting when keeping the speedo at 90 and approaching well known bends at a visually faster rate. Or conversely approaching at your normal speed and thinking , Is this speedo under reading? ( Old ,tired ,brain, stuck in a rut. )

 

[Rolfe]

My car speedo and the council signs are in complete agreement.

 

[ReintjeWA]

This is good info to have, I'm so used to just tack an extra 5 km/h onto my cruise control because that used to be the deviation in my last few ICE cars. Guess I'll have to unlearn that behaviour now.

 

[JonnyG]

................Let me tell you 30mph feels soo fast! ................

 

[siteguru]

Maybe I should test with GPS app on phone? In which case, any recommendations?

Waze and AmiGO satnav apps include a speed reading based on GPS speed calculation, and they're compatible with Android Auto/Car Play so you can see the info on the car screen.

 

[Deleted member 16414]

My local council have put up speed awareness signs on various roads near me recently. I've noticed that the speed the sign says I'm doing is 2 mph higher than the speed displayed on the dashboard. I thought speedos aren't allowed to under read, and that at speeds lower than 30 mph tend to over read.

So is my speedo working correctly, or are the council signs calibrated to read high? (possibly to get drivers to slow down more) Maybe I should test with GPS app on phone? In which case, any recommendations?

Mine mg 4 24 done it from day one all they said they have look when service