[Noodles]

On many of the roads here we are required to do 20 MPH.

In the last two days, three people have told me they have been fined etc.

So I’m thinking of buying a heads up digital display GPS Speedometer so that I can see my speed more clearly.

There are sooooo many to choose from, I don’t know where to start and what’s a reasonable amount to pay?

[Drivingforfun]

I bought one several years ago for my first car, I had a Mini which had the speedo in the centre console and I wanted to be able to see my speed in the usual place behind the steering wheel

I got a decent one and it was more accurate than the car speedo, my car apparently over-read by around 1.5-2 mph

If it's just because of the 20mph limits though, I don't think you need to overly worry about accuracy. Car speedos legally have to overestimate (if they're not spot on), also, while not guaranteed, cameras are known to offer a little leeway. So without sounding condescending, just stick vaguely to the limit and you'll not get into any bother

[Drivingforfun]

Just to add I think there was something about the GPS speedo also not being entirely accurate either. If I remember right, they are accurate at sea level but anything above (or below I suppose) sea level they're a bit off. It's to do with the fact that the distance to travel around the world gets longer as altitude increases but this isn't taken into account so it will understate your speed...I think it's probably by a negligible amount but just might be worth taking into account

[Noodles]

Cheers Driving for fun,

I’m waiting to hear if I’ve been ‘done’ as I’d just come off a dual carriageway onto a 20 and the police were hiding at the bottom of an incline :) and although I was slowing down it may not have been enough. It’s difficult to slow down on a hill! I tend to use my gears to slow down as it’s easier than setting your brakes on fire!! (That last bit is a joke) :0

[olduser]

Have a look at you satnav's settings, there may be an option to show your current speed, and if it's mapping info is up to date it will show the immediate speed limit, and will issue an alarm if you are over the limit.
I am not sure but I think the phone based satnav's automatically up date.

[Mark07]

Originally Posted by olduser

Have a look at you satnav's settings, there may be an option to show your current speed, and if it's mapping info is up to date it will show the immediate speed limit, and will issue an alarm if you are over the limit.
I am not sure but I think the phone based satnav's automatically up date.

I'm unsure how accurate it is, but Google Maps shows your speed as you're driving, I'm assuming that it operates based on GPS data.

[olduser]

With the satnav app being on a phone, it has two options for speed.
It is likely using GPS data to calculate speed but it could use the phone masts it's pinging but either way the calculations and errors will be about the same.

[Rolebama]

It used to be that a speedo had to be 100% accurate up to 30mph. It was only above this speed that you were allowed 10% + or -. I assume this is still the case? I have been told by a number of Police Officers that over 30mph they would also give you an extra 2mph before they would prosecute. Again, I also assume this is still the case, which would explain why the M4 safety cameras were set to allow up to 79mph before triggering.