TomTom 3 - Speed indicator

#1 (**permalink**) 10-02-2005, 09:10 AM

How accurate is the speed indicator on TT3?

On the motorway yesterday travelling at 70 (according to my speedo), yet TT3 was showing my going 64. Travelling at 40 (speedo), TT3 said I was doing 36...

#2 (**permalink**) 10-02-2005, 10:00 AM

Same here DaveA But in my case its the cars speedo(old peugeot 405) that's over reading ,because if I try the same test in my BMW both speedo and GPS are within 1 mph of each other.

**Charlie** · #3 (**permalink**) 10-02-2005, 10:20 AM

There has been discussion before over which is the most accurate but it depends on lots of different factors. I get the same results, my GPS reads about 5mph over my speedo.

#4 (**permalink**) 10-02-2005, 12:21 PM

Most speedo's are a little optimistic,But as I mentioed previously my Peugeot is definitely over optimistic.

You could always time yourself over a Motorway mile between two junction exit signes at 60mph which should take exactly 1 minuete.

**Charlie** · #5 (**permalink**) 10-02-2005, 12:58 PM

I've tried it with the missus in here car doing 60mph on her speedo to see what I'm doing and what the GPS says but it still left the possibility that her speedo is wrong as well

I'll try it your way Delboy.

#6 (**permalink**) 11-02-2005, 07:53 PM

I can just see it now .....

"Well Officer, it was like this ......... I may have been travelling 100mph but it was a scientific test to see whether the Odometer or the GPS....... "

#7 (**permalink**) 18-02-2005, 08:37 AM

does the Ipaq 1710 HP Navigation Pack & POI show the speed?

#8 (**permalink**) 01-03-2005, 03:31 PM

Quote:

Originally Posted by DaveA

How accurate is the speed indicator on TT3?

On the motorway yesterday travelling at 70 (according to my speedo), yet TT3 was showing my going 64. Travelling at 40 (speedo), TT3 said I was doing 36...

'Vehicle construction and use regulations require a vehicle speedometer accuracy to be in the range of -0->+10%. The implications are that it must never under-read - for obvious reasons - but may over-read.'
If you are interestd the above quote comes from the Association of Chief Police Officers web site on this subjuect. Basically, if you are looking for a speedometer that is 100% they are available but cost a fortune.
Hope this helps
Brian

#9 (**permalink**) 02-04-2005, 08:16 AM

I have an ex police Omega MV6 with a specialist calibrated speedo (has a sticker on it to say so, if it's right for them then it must be ok) and my TomTom reads about 4mph over, i think it can depend on several things like which receiver you are using and how fast your processor is, also how fast your map card access is