I know the fuel computer is notoriously inaccurate!, but how accurate is the digital speedometer? - I ask because when running at a cruise control set 60mph I don't seem to be going any faster than HGV's which I think are limited to 56mph! And at 70mph I've had coaches go faster than me on motorways (they have tachographs so I'm assuming they adhere to speed limits!)
Anyone checked against some form of GPS speed app to give an idea of inaccuracies at different speeds?, the Disco SatNav does not appear to have any speed function on it!
25th Jun 2016 1:32 pm
JustaGeek
Member Since: 25 Apr 2015
Location: Round the Twist
Posts: 79
My speedo @ 60 mph, reads within 1mph of every sat nav app I've tried.
As for coaches, National Express didn't get that name by accident, they earned it, and every driver seems hell bent on proving it.
25th Jun 2016 1:44 pm
DSL Keeper of the wheelie bin
Member Since: 11 May 2006
Location: Off again! :-)
Posts: 72791
My speedo is pretty much bang on and virtually always cruise at 60. Nicely faster than trucks and coaches go past me with a few mph difference. Eccosse, U running on standard tyres?
25th Jun 2016 3:21 pm
trevorb1
Member Since: 21 Mar 2015
Location: Nuneaton
Posts: 62
Checked against Garmin satnav and some of the road side speed signs, digital over reads by about a consistant 2mph, 15my running Goodyear wranglers on 19 inch rims
Will see if I can get a Garmin to try - suspect it is 2-3mph over-reading, as even at 30mph some of the warning speed signs show it as only 27/28mph! - is that unusual or reasonable on a modern car?
25th Jun 2016 5:23 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
It is designed to over-read. The system is capable of an accuracy only limited by the varying wheel circumferences; the over-reading is accomplished in the software.
Land Rover - Turning Drivers into Mechanics Since 1948
The UK law is based on the EU standard, with some minor changes. A speedo must never show less than the actual speed, and must never show more than 110% of actual speed + 6.25mph. So if your true speed is 40mph, your speedo could legally be reading up to 50.25mph but never less than 40mph. Or to put it another way, if your speedo is reading 50mph, you won’t be doing more than 50mph but it’s possible you might actually only be travelling at 40mph.
To ensure that they comply with the law and make sure that their speedometers are never showing less than true speed under any foreseeable circumstances, car manufacturers will normally deliberately calibrate their speedos to read ‘high’ by a certain amount. As your satnav is not the designated device by which a car’s speed is measured, it does not need to incorporate any fudge factoring.
My experience is they typically over read by around 2-3mph depending on wear of tyres
My MY2012 D4 is a consistent 3 mph out - It is quite annoying
Running standard 255/50/20 Scorpions
Is there a way to tweak it back using IId or similar ?
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25th Jun 2016 6:14 pm
lynalldiscovery
Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274
Rough rule I always work on in all cars is speedo is 5 percent fast so all limits can be exceeded (where appropiate) by 10 percent on the clock and you will still be legit.
Ie 77 on the clock is most likely a real 72/73mph.
25th Jun 2016 6:20 pm
DSL Keeper of the wheelie bin
Member Since: 11 May 2006
Location: Off again! :-)
Posts: 72791
I won't do that on mine as 77mph on the dial means 77mph in reality on mine.
25th Jun 2016 6:35 pm
nazca sand eddie
Member Since: 29 Oct 2015
Location: England
Posts: 41
MY 16, on Wrangler 19".
Compared to Garmin Sat Nav and French Radar readouts, I am a constant +2mph or +4kph.
That is actual 30 = shows 32, actaul 50 = shows 52mph.
actaul 40 =shows 44, actual 90 = shows 94 kmp.
Compared to my last two Freelander2s they were either spot on, or showing +1 mph.
Like others have commented, rather annoying, especially on the continent.
25th Jun 2016 6:45 pm
CUCO
Member Since: 27 May 2011
Location: Spain & Oleee!!!
Posts: 609
Is the setting adjustable? iidtool maybe?
26th Jun 2016 1:25 am
lespes
Member Since: 17 Sep 2009
Location: Sitting Down
Posts: 2232
Its a feel good measure provide FOC by Landrover.
Gives you more mpg D4 Landmark MY16 Santorini Black THE LAST
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D4 HSE MY11 Silver: Gone missed !
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