Member Since: 21 Dec 2017
Location: Leominster
Posts: 279
Do you consider your speedo accurate.
Sometimes in those roadworks, or smart motorway situations, I find people doing different speeds to me. Is it their stupidity, their Speedo’s, or my speedo.1955 SWB Series 1 86 inch
1960 SWB Series 2 88 inch
2009 Discovery 3 HSE Bournville Pearl
15th May 2020 12:44 pm
RogB
Member Since: 15 Jun 2018
Location: Mansfield
Posts: 1693
basically no speedo is accurate as rule of thumb. your speedo could be saying 70mph, so could the guy's speeding past you.
lots of factors influence speedo readings which is why a zero tolerance policy by the police would be lunacy, they would be hit with so many people pushing to court hearings because of unavoidable inaccuracies.
my speedo reads 70mph but according to Waze satnav on my phone im doing about 67mph. I think all mass manufactured cars speedos are set to read slightly high.2011 D4 XS 305 MY12 - gone but not forgotten
15th May 2020 1:04 pm
Scott #55
Member Since: 15 Apr 2015
Location: Glasgow
Posts: 1681
I've got to disagree. I think that the one in my Disco is unerringly accurate.
I usually drive at the speed limit and, any time I pass one of these machines which flashes your speed up, it always reads 3mph less than what the speedo says. Doesn't matter where I am, it's always 3mph less on the roadside monitor.2014 - D4 2010 HSE Nara Bronze
2012 - FL2 2009 GS Stornoway Grey
2001 - VW Passat Estate Inky Blue
1999 - Ford Mondeo Light Blue
1998 - Rover 25 Red
15th May 2020 1:09 pm
rrhool
Member Since: 28 Aug 2014
Location: Norfolk
Posts: 4469
Of all the cars I've had, my D3 is the most accurate. I've checked it against a Garmin satnav, GPS dash cam, and all those flashing speed signs that show I'm doing 31 in a 30 limit!
I know none of those things are in themselves calibrated, but as an average they all measure about the same.
My car shows about 71/72 for 70 on the satnav. 30 is spot on, and similarly accurate between 30 & 70.
SWMBO's Corsa is a good 7-10% fast all the way up. Most cars read fast now, in an attempt to slow people down. It only has the same effect as setting your watch 10 minutes fast to try to be on time for things!Richard
D3 SE 2007. Triumph 2.5Pi 1973. Ferguson TEA20 1948.
Discovery 2 4.0 ES 2001- Gone
Discovery 1 300Tdi ES '95 - Gone
Range Rover Classic '79 - Gone
15th May 2020 1:11 pm
Motolab
Member Since: 18 Oct 2019
Location: Sleen
Posts: 1820
Re: Do you consider your speedo accurate.
Grandadrob wrote:
Sometimes in those roadworks, or smart motorway situations, I find people doing different speeds to me. Is it their stupidity, their Speedo’s, or my speedo.
there can be more reasons but
the actual speed and the dail speed, changes also if you change tire sizes... if not changed in your or their ECU, bigger or smaller tires will give different speeds as with factory standard.. so wil theirs...
who is running what? you never know, but also, everything will not be the same calibrated...
the only thing you can do is, read your speed on a Navigation/GPS and match the calibration in the appropriate ECU of the motor so it matches...
IID can change that data.. maybe also others.. the difference with other motors beside you on the road will stay however since they do not calbratie their ECU"s with their tires and stupiduty is not something to be calibrated anyway i am afraid.. Best regards
Harold
Always looking for Pre '55's & Pre war British Motorcycles! knowing or having one for sale? PM please. I visit the UK 6 times a year
Ps. I edit my texts quite often, english is not my native language, so I will edit My “typo’s” etc.
15th May 2020 1:26 pm
Oswiperus D3 Decade
Member Since: 02 Apr 2010
Location: Chelmsford, Essex
Posts: 1595
My D3 is pretty accurate.
My D4 did over read until I fitted 255/55/20 as opposed to 255/50/20 and now it's near as dam it spot on.Stu
2016 D4 Landmark current
2022 Defender D300 SE Gone
D4 2014 XS Commercial - Gone
D4 2016 hse lux montalcino red - Gone
D3 2005 se java black - current
D3 2005 base manual - gone
D2 1999 TD5 E white - current
15th May 2020 2:20 pm
L319
Member Since: 14 Dec 2013
Location: Herefordshire
Posts: 2081
My D3 is the most accurate speedometer on a vehicle I have. Speed indicating devices and sat navs. all seem to agree within about 1mph with the reading .. It topped out reading 115 mph on the Autobahn , the vehicle being governed to 112 MPH according to my engineer colleagues at Land Rover
15th May 2020 2:31 pm
al cope
Member Since: 08 Nov 2005
Location: Oldbury, WM
Posts: 10336
Under UK law - which is based on a European Union standard - speedometers must never underreport a vehicle's speed, while it must never overreport by more than 110% of the actual speed + 6.25mph.
So if you’re going 40mph, your speedometer may read up to 50.25mph - but it can never read less than 40mph. In order to stay within the law, carmakers calibrate their speedomters to slightly overreport their vehicles' speeds.
AlVolvo XC90 B5 Plus Dark
Gone - MY18 D5 HSE - Corris on 22's with Black Pack
Now gone - MY16 D4 SE Tech, Loire Blue, Almond Leather, Privacy, plus some other goodies.
Old - MY12 D4 SDV6 XS Auto - Ipanema Sand with Almond Leather - Plus other niceties, and D4.com sticker
Older - D3 TDV6 XS Auto - Lugano Teal with Almond Leather, 20" Stormers, Shiny Tailpipes, DVD/TV - and obligatory D3 sticker
Ancient - D3 TDV6 S - Tonga with Ebony, 20" Stormers, satnav & DVD
15th May 2020 3:37 pm
aja4x4
Member Since: 14 Apr 2019
Location: Westbury
Posts: 2462
My D3 was very accurate when i had it tested, my D4 commercial had gone in for a tacho calibration and was within a few mph when tested and i asked if i could put my D3 on the rollers and with new tyres it was virtually reading the correct mph.
Its handy to know as with my old cars i knew they read 10% high and could go a little faster on the speedo but still stay leagal
Coming from a classic/time/distance rallying background I am very aware of exactly what you say.
The problem is that the vast majority of drivers are unaware of this, and some are reluctant to allow one to overtake although they are doing substantially less than the mandatory speed limit.
NJSSAm I Gammon or Woke ? - I neither know nor care.
2016 Discovery 4 Landmark
2011 Mercedes Benz SL350 (R230)
1973 MG B GT V8 - 3.9L John Eales engine, 5 speed R380 gearbox, since 1975.
1959 MGA roadster - 1.9L Peter Burgess Engine - 5 speed gearbox
Past LRs - Multiple FFRs, Discos & a Series I - some petrol, some diesel,
none Electric or H2 fuel cell - yet.
There are 10 types of people in this world: Those who understand binary, and those who don’t.
15th May 2020 6:53 pm
Leon
Member Since: 26 Apr 2014
Location: Leamington Spa
Posts: 434
My disco Speedo is near enough spot on, my mercedes vito works van (brand new)is way out e.g. 55 on Speedo is actualy 50, I have to get Speedo to 77 to be travelling at 70.
Have to keep remembering in disco not to push the speed up to much.
16th May 2020 2:53 pm
DSL Keeper of the wheelie bin
Member Since: 11 May 2006
Location: Off again! :-)
Posts: 72947
D3 was spot on, D4 was over reading by a few percent.
16th May 2020 2:55 pm
J.Prezes
Member Since: 10 May 2015
Location: usually at my Indy's shop
Posts: 62
my D3 is almost perfect 255/55/19. but for example my subaru always reads 10% over the actual speed
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum
