Whats more accurate

[Zugara]

Your speedo or your satnav indicated speed. Dont know if anyone has noticed the satnav speed is always different from your speedo.

 

Wondered if anyone knows which ones more accurate?

[ATTAK Z]

Satnav

[Ruddles]

Think the speedo is the more accurate, they're usually 1-2mph out I 'think'! Whereas the satnav works on average distance covered I think you'll find!

[Demolition49]

I would of said at lower speeds speedo is more accurate and at higher speeds the sat nav is more accurate

[clarkie34]

I would go with satnav being more accurate.

[ATTAK Z]

Speedos can by law be up to 10% out ...... manufacturers design speedos to be within the law but always on the PLUS side (i.e. they can read up to 77 at a true speed of 70 mph) ..... They do this to avoid being sued when you get caught for speeding

 

A good satnav will read your position to within 10 metres and time very accurately so speed is accurate also. It will not however take into account the 'faceting effect' around long bends

[Demolition49]

yes but a speedo will be more accurate at lower speeds because a gps cant keep track of each and every meter so for example

 

at 10mph the speedo can be out by 1mph where as a gps might not pick up what your doing... and so on

20 mph 2mph error

30mph 3mph error and so on...

[ZMANALEX]

I would think that GPS is 100% accurate.

[ATTAK Z]

yes but a speedo will be more accurate at lower speeds because a gps cant keep track of each and every meter so for example

 

at 10mph the speedo can be out by 1mph where as a gps might not pick up what your doing... and so on

20 mph 2mph error

30mph 3mph error and so on...

It depends on how often the satnav receives the signals ......... and some speedos don't come off the stop until you're doing 10 mph

[Ekona]

Satnav by far.

 

That said, on my old VXR220 the speedo was exact with the satnav, so Vauxhall/Lotus obviously have a lot of faith in their faux-Stack dash.

[Demolition49]

yes but a speedo will be more accurate at lower speeds because a gps cant keep track of each and every meter so for example

 

at 10mph the speedo can be out by 1mph where as a gps might not pick up what your doing... and so on

20 mph 2mph error

30mph 3mph error and so on...

It depends on how often the satnav receives the signals ......... and some speedos don't come off the stop until you're doing 10 mph

 

Fair point,

 

but hey at the end of the day when you come to a camera just go under the limit not ON the limit and we should all be ok unless you have horribly huge or small wheels!

[alessandro]

At speed, I have a differ ence of nearly 10mph between the speedo and the sat nav

[Husky]

sat nav unless your going slow enough you cant even read the speedo

[mattbowey]

gps locates about 14 satellites at any one time and uses them to pinpoint your location. it was originally used byt the us army and then released for use by the general public as the satellites were up there costing a lot of money and can multitask anyway.

 

based on that,

 

i'd trust the gps more than the speedo, mine are always pretty close together though

[Husky]

gps locates about 14 satellites at any one time and uses them to pinpoint your location. it was originally used byt the us army and then released for use by the general public as the satellites were up there costing a lot of money and can multitask anyway.

 

based on that,

 

i'd trust the gps more than the speedo, mine are always pretty close together though

*cough* wikipedia *cough*

[mattbowey]

gps locates about 14 satellites at any one time and uses them to pinpoint your location. it was originally used byt the us army and then released for use by the general public as the satellites were up there costing a lot of money and can multitask anyway.

 

based on that,

 

i'd trust the gps more than the speedo, mine are always pretty close together though

*cough* wikipedia *cough*

 

*cough*military presentation i had to do during my training and before i was injured which i then used for my college course i am on now *cough*

[Husky]

gps locates about 14 satellites at any one time and uses them to pinpoint your location. it was originally used byt the us army and then released for use by the general public as the satellites were up there costing a lot of money and can multitask anyway.

 

based on that,

 

i'd trust the gps more than the speedo, mine are always pretty close together though

*cough* wikipedia *cough*

 

*cough*military presentation i had to do during my training and before i was injured which i then used for my college course i am on now *cough*

*cough*show off*cough*

[Chris`I]

Gps can be more accurate, but lots of things effect it. For purposes if determining your speed for driving nor ally, use the speedo, they are designed to overread as by law they can't under read so will always keep you safe. Saying that gps should be more accurate at speed with a good lock of satellites.

 

The best combo is to use both like oem satnavs can using gps and speedo to calc actual speed

[rich5259]

My satnav is the same as the digital speed read out in the Zed, the speedo is 1 or 2 mph behind at 70 MPH.

 

In the X-trail the speedo is 10% fast at all speeds, a known "fault" on the 2.2 diesels

[Chris`I]

Another thing to remember is that IIRC all the different Zed spec wheels have slightly different rolling radius (radii?) and thus the speedo will read slightly differently depending on which wheels you have. With my Rays the GPS was ~2MPH faster than the digi readout, and that was ~3MPH faster than the speedo at 70MPH.

[zDan]

GPS would be more accurate in reporting the true speed... HOWEVER.... GPS is not instant! I found GPS to have a lag between 1-2 seconds, if not more when reception is poor. Which makes it a bit useless IMHO because you can never tell your speed when you need it.

 

The moral of the story is that if you are driving on constant speeds with a clear GPS reception on a straight line then GPS is the accurate one. But don't rely on it when "adjusting" your speed for a speed camera you just saw, cause it may still show you the speed you had 10 seconds or a minute ago...

[ATTAK Z]

GPS + cruise is the ultimate combination for 70 60 50 and 40 m/h zones

 

 

 

 

end of

[martinmac]

At a steady speed the GPS will be very accurate. There is a slight time lag though. The modern Sat Nav is very accurate. Out marine system is pretty good up to a couple of metres and coupled to electronic charts makes life a lot easier.

[Chris`I]

We just all need military spec GPS recievers then we'd be sorted