SGK
Member Since: 09 Jun 2006
Location: Melbourne
Posts: 40
  
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Hi there,
When Speedometer shows me doing 50km/h, I am doing 46km/h according to the GPS.
When Speedometer shows me doing 100km/h, I am doing 94km/h according to the GPS.
When Speedometer shows me doing 110km/h, I am doing 104km/h according to the GPS.
This is the one thing about my D4 which I find annoying, especially with the digital readout on the instruments which makes you feel it should be more precise. My D3 wasn't so much off.
According to the dealer this is within specifications and they can't and don't know how to change this, anyway.
I was always under the impression that at 50 km/h the speedometer should be pretty much spot on - and at 100k/mh slightly under. But under by 6km?
Is this really within specs? Is there really nothing the dealer can do to recalibrate the speedo?
At the moment I am using the GPS for speed - but that's not really a great solution, and constantly trying to calculate the speed isn't what I want to do, either.
Does anyone have any advice for this?
sgk Prado Grande --> D3 --> D4 ... its getting better all the time
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 25th Feb 2010 12:10 pm |
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sandylane
Member Since: 20 Dec 2009
Location: Berkshire
Posts: 74
 
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Looks like your speedo is working fine then......
Manufacturers ensure around a 10% over-read on speedos so they can't be sued for cause of speeding
 Club D4 XS
Club Pirelli Scorpion ATR
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| 25th Feb 2010 12:54 pm |
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ad15
Member Since: 14 Dec 2008
Location: up that tree
Posts: 4866
 
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if you try driving a rover, 70mph is actually 62mph.... they're way out,
as said above, so they can't be sued...
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| 25th Feb 2010 12:58 pm |
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TSR2
Member Since: 22 Jul 2008
Location: North Lincolnshire
Posts: 1104
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And then of course there's the question of the accuracy of the GPS?? 
Anyone happen to know what that is??  Regards, Trev.
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In the wilds of North Lincs or the middle of the North Sea.
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| 25th Feb 2010 1:13 pm |
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Alicatt
Member Since: 10 Jul 2007
Location: Eating in Eksel or Working in Wick
Posts: 320
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Changed from the standard 20" wheels and tyres to 19" wheels with 255/55 R19 MT/R tyres and that made the speedo under read compared with the GPS, tho the cruise control is now spot on 
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| 25th Feb 2010 1:23 pm |
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OzDisco
Member Since: 14 Nov 2009
Location: Sydney
Posts: 26
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I was going to say, just drive everywhere at 10kmh over the limit....
....but then I noticed you are in Melbourne!!!!
Would be interesting to know how accurate the GPS is though. Life is not measured by how many breaths you take, but by how many moments that take your breath away...
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| 25th Feb 2010 6:45 pm |
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GraemeS
Member Since: 17 Mar 2008
Location: NSW
Posts: 706
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My D2 speedo agrees with my GPS yet my D4 speedo is wrong as reported above. Its poor that a vehicle so reliant on electronics has a dud speedo, especially when it displays the numbers implying it it correct.
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| 25th Feb 2010 9:13 pm |
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TSR2
Member Since: 22 Jul 2008
Location: North Lincolnshire
Posts: 1104
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GraemeS,
In Britain I believe it is illegal for a car manufacturer to fit a speedo that reads lower than your actual speed, or so the debate on this previously uncovered. This may also be the case in other countries so I don't think that they are innaccurate because they have made a poor product more a reluctance to approach the level at which they may get fined or have to remove them from the car. They may be working from a + zero -10% accuracy range. Accurate measuring equipment is very expensive and I suppose they believe that we would not want to pay the extra cost.
It still intrigues me that you appear without question to believe the sat nav speed.
PS I find mine is 2 mph lower on average than the sat nav. Regards, Trev.
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In the wilds of North Lincs or the middle of the North Sea.
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| 25th Feb 2010 10:54 pm |
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DG
Site Moderator
Member Since: 12 Dec 2005
Location: The Gaff
Posts: 50978
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Quote:The amended Road Vehicles (Construction and Use) Regulations 1986 permits the use of speedometers that meet either the requirements of EC Council Directive 75/443 (as amended by Directive 97/39) or UNECE Regulation 39. [12]
The Motor Vehicles (Approval) Regulations 2001[13] permits single vehicles to be approved. As with the UNECE regulation and the EC Directives, the speedometer must never show an indicated speed less than the actual speed. However it differs slightly from them in specifying that for all actual speeds between 25 mph and 70 mph (or the vehicles' maximum speed if it is lower that this), the indicated speed must not exceed 110% of the actual speed, plus 6.25 mph.
For example, if the vehicle is actually travelling at 50 mph, the speedometer must not show more than 61.25 mph or less than 50 mph. There is also the added problem of cars not complying with the United Nations standards, being imported and allowed to be registered, making the situation even more complicated. This needs further investigation.
21 year LR veteran > D2 GS 2003 > D3 S 2006 > D3 HSE 2009 > D4 HSE 2013 > D4 HSE 2015 > D5 HSE 2018 > DS HSE R-Dynamic P300e 2021
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| 25th Feb 2010 11:13 pm |
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TSR2
Member Since: 22 Jul 2008
Location: North Lincolnshire
Posts: 1104
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There you go...thanks DG.. Regards, Trev.
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In the wilds of North Lincs or the middle of the North Sea.
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| 25th Feb 2010 11:15 pm |
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DG
Site Moderator
Member Since: 12 Dec 2005
Location: The Gaff
Posts: 50978
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"UNECE Regulation 39" also applies in Australia for any vehicles built after 2007 21 year LR veteran > D2 GS 2003 > D3 S 2006 > D3 HSE 2009 > D4 HSE 2013 > D4 HSE 2015 > D5 HSE 2018 > DS HSE R-Dynamic P300e 2021
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| 25th Feb 2010 11:17 pm |
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SGK
Member Since: 09 Jun 2006
Location: Melbourne
Posts: 40
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SatNav speed is used in various sports to measure world records. While the positioning may be off - the speed will be accurate.
I have also on some occasions tested the GPS against Speed camera readings - i.e. near Melbourne there are a number of bridges with displays which will tell you how fast you are actually driving when passing the camera - the GPS was spot on every time.
I also know how fast I can drive on the Freeways without speed cameras taking offence. If the car was doing the speed the speedometer shows, I would be paying every day.
Is there a way for Landrover service to calibrate the Speedometer?
sgk Prado Grande --> D3 --> D4 ... its getting better all the time
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| 25th Feb 2010 11:17 pm |
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TSR2
Member Since: 22 Jul 2008
Location: North Lincolnshire
Posts: 1104
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SGK,
I'm not at all surprised by what you state but I would suggest that the sat nav equipment they have is far more accurate and expensive than our common or garden sat nav systems.
As for the radar speed trap / indicators there is enough evidence to prove that in all but ideal conditions and set up these are also extremely unreliable (not necessarily innaccurate) as a number of our police forces have found out in court.
I don't disagree with you I think my sat nav is pretty good bearing in mind that the speedo is always going to read low but you can't guarantee the accuracy. I have also noted big deviations in indicated speed on the sat nav possible due to only being connected to one or two satellites. Unless I have a cheap piece of cr*p. Regards, Trev.
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In the wilds of North Lincs or the middle of the North Sea.
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| 25th Feb 2010 11:35 pm |
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SGK
Member Since: 09 Jun 2006
Location: Melbourne
Posts: 40
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So it is legal and within specs - thanks to everyone who has answered so far.
However it is very consistent in showing me the same difference between speedometer and GPS speed.
But what I'd really like to know is if there is a way for Landrover to recalibrate the speedometer.
I understand this is a pet hate and almost everyone else is fine with the fact that Speedometers don't have to read accurately. But I find it annoying, and the difference is consistent accross the board pretty much. So if it could be calibrated to be correct at 50, it will be nearly correct at 100 - which is good enough for me.
sgk Prado Grande --> D3 --> D4 ... its getting better all the time
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| 26th Feb 2010 12:09 am |
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chalky
Member Since: 21 Aug 2008
Location: Yorkshire
Posts: 3145
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I,m not sure if there is a way for the instruments to be re calculated, However if you do find out then please spread the gospel as i find this increasingly frustrating.
On the GPS accuracy, Seeing 1 or 2 Sats any system will be massively inacurate 2D and should give the systems last known Location, seeing 3 sats again will at best put you way off but somewhere near for instance driving up the Motorway might see the system plotting you on an A road adjacent, for a 3D fix ANY GPS based reciever must see at least 4 Sats.
For all intents and purposes the timed signal from the Sat to the reciver in your Sat Nav takes a specific time, this is how they plot exactly where they are.
I cant speak for all systems however the kit i use at work is spot on.
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| 26th Feb 2010 2:10 am |
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