Speed Query

Being a law abiding and an upright citizen I always watch my speed.

Trouble is my car says I am doing 68 and TomTom says I am doing 75.

I assume that TomTom is so darn accurate that the speed camera will take a photo to prove it, but am I right to think so?

I know car speedos are not 100%, but who should I trust?

The difference between my tomtom and speedo is usualy around 3 - 4 miles per hour. As a rule, I tend to take my cars speedo as true as this is normally the higher figure. This way i know that no matter which is right, I am going at the speed limit or lower ;0)

Originally Posted by Crusher

Trouble is my car says I am doing 68 and TomTom says I am doing 75.

My gps always reads lower than the car? Depending which car I'm in but generally 4-7mph less than the car

This is obviously quite standard then

[Stevie]

you will find in most cars the speedo is set to be doing greater than what you are actually doing. The GPS is prob more reliable as if you are doing 30 on ur speedo your prob doing 25-28mph, but dont blame me if u get caught speeding :-)

I had this issue with my previous Road Angel 2. My tachograph in my lorry which is calibrated tells me I am doing 56mph. The Road Angel told me I was doing 54mph. I rang Blackspot and told them of this difference and the technical advisor told me that GPS was 100% correct and my tacho was out. I then also drove different lorries and the result was the same..


I now have a Tomtom Go 700 and this is telling me much the same via the GPS, 56mph on the lorry tacho and 54 on the TTG sat on the dashboard.

Make of it what you will..

You only have to think about it, vehicle speedo's have to read on the safe side, they have to keep you the right side of the law whether you have new tyres with 8mm of tyre tread or worn ones with 1.5mm, low tyre pressures will also affect the rolling circumference. They convert the number of revolutions of your final drive to mph, on a 13" wheel the tyre tread alone could alter the number of revolutions per mile by up to 25, 3% this can be made worse by running your tyres with less than the specified psi.
I read somewhere that in europe our speedo's are callibrated on the safe side where as in the States they work on an average over the tyres life which gives you a more realistic figure

Just checked my speed today and its 2mph higher on the cars clocks.

I too am one of those law abiding citizens (well not anymore) After 13 years of no speeding fines I got myself a tom tom and behold no more then 11 months later a speeding ticket.

Scenario.

Speedo says I am doing exactly 35mph, Tom Tom says I am doing 30mph.

There I was trundling in my van down a road and FLASH I get caught. Thinking it was the car next to me that had been flashed I continued.

100m down the road and still my speedo says 35mph and my tom tom says 30mph FLASH i get done again with no-one on the road apart from me.

14 days later 2 court (speeding issues) fines appear on my doorstep asking me to fill out my details and accept that I was the driver. I did and sent them back 1 week later the fines appear 3 points for each offence and £60 fine for each offence.

So I contested it and was told that the camera's are calibrated in a 30mph zone to go off at 35mph. The use of any gps receiver or any other equipment will not and can not be usedin any defence if i was to choose to contest the fines. The only two things that they would allow is a) my speedo b)their camera so since their camera is correct that means only my speedo can be wrong. Since my speedo was not wrong as it WAS showing 35mph and since the camera went off at 35mph and the photo they kindly send you.

Any the tale of this story is dont trust the speed of your gps to be correct otherwise you may end up like me. £120 down 6 points on my licence insurance company rubbing its hands together and a company that has the rule that if you have more than 3 points on your licence then you cannot be employed. So now im up s*** creek without a paddle

Damn, that is harsh Nutski. I hope you get everythin sorted tho (especially job wise)