How accurate are GPS speedos?

1303Steve Scirocco Rare

8,650 posts · joined Aug 2002 · 1 Dec 2008, 10:32 pm

#682563

Hi

I have a Garmin GPS that I use in my 2008 Toyota Hi Lux work ute.

According to speedo in the GPS the Toyota speedo is way out, at 110 kph indicated on the GPS speedo, while the Toyota speedo reads 120 kph.

Anybody have any thoughts?

Steve

Brad Wolfsburg Elder

3,764 posts · joined Aug 2002 · 1 Dec 2008, 10:35 pm

#682565

The GPS should be accurate at speed

Brad
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4,674 posts · joined Aug 2002 · 1 Dec 2008, 11:17 pm

#682574

I've got numerous GPS units, and they all seem to agree with each other...... 😂

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Sioux Seriously Crusin Dubber

178 posts · joined Jan 2007 · 1 Dec 2008, 11:52 pm

#682577

iv got a garmin nuvi 250w and have tested it in several cars against the speedo.

in a '06 falcon XR6 @ 60kph gps indicated the speedo was at 68kph

in a '07 mitsubishi express van @ 60kph gps indicated speedo was at 74kph, @ 100kph gps indicated speedo read 121kph

in a '03 mitsubishi magna @ 60kph gps indicated, speedo reads 54kph, @100kph gps indicated, 108kph

on a '06 520hp turbocharged nitrous suzuki hayabusa on a certain stretch of freshly laid bitumen @ 250kph gps indicated speedo read 251 kph. (i wasnt riding it...bugger that ! )

i also used a navman 610 widescreen at the same time in the falcon, magna and van and both GPS's indicated the same speed. the garmin is a bit slower to update the speed though.

oh i forgot to mention, after 39 years my beetle's speedo is spot on ! from 0kph to 130kph !

VWCOOL 23 Windows of Awesome

5,158 posts · joined Jun 2003 · 2 Dec 2008, 12:25 am

#682581

1303Steve wrote:Hi

I have a Garmin GPS that I use in my 2008 Toyota Hi Lux work ute.

According to speedo in the GPS the Toyota speedo is way out, at 110 kph indicated on the GPS speedo, while the Toyota speedo reads 120 kph.

Anybody have any thoughts?

Steve

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eraser Fahrvergnugen

970 posts · joined Mar 2005 · 2 Dec 2008, 5:49 am

#682588

The only minor problem is when they loose satellite connection they just guess, e.g tunnel or heavily treed area you can be doing 100 then slow down to 20 and it will just assume your going 100 all the way (untill its next update)

donn Wolfsburg Elder

3,515 posts · joined Nov 2005 · 2 Dec 2008, 7:03 am

#682593

oh i forgot to mention, after 39 years my beetle's speedo is spot on ! from 0kph to 130kph !
Yep, I had a car once that took nearly that long to get there.😂
My Garman Nuvi reads 3kmp faster at 70 on the speedo of the Crewman, at 100 k on the Crewman speedo the Garmin reads about 104, so I drive by the Garmin (can no longer afford to get sprung, on a good behaviour licence)

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rose doin it for d girls

2,036 posts · joined Dec 2004 · 2 Dec 2008, 7:09 am

#682594

The gps is correct our Toyota Hilux is out the same as the car is made in Tialand what do you expect..

Only out huge like this in our Toyota. Other cars are only out by a couple of klms.

Haven't you noticed people going past you before you got your gps. As when your doing 100 on your speedo your really only doing 90 so your'll never get booked for speeding.

1303Steve wrote:Hi

I have a Garmin GPS that I use in my 2008 Toyota Hi Lux work ute.

According to speedo in the GPS the Toyota speedo is way out, at 110 kph indicated on the GPS speedo, while the Toyota speedo reads 120 kph.

Anybody have any thoughts?

Steve

eraser Fahrvergnugen

970 posts · joined Mar 2005 · 2 Dec 2008, 4:37 pm

#682665

yeah the subarus and some toyotas are out by 10kms on purpose, something to do with speeding prevention.

Baja Wes V6 Baja Pioneer

3,119 posts · joined Aug 2002 · 2 Dec 2008, 5:20 pm

#682676

They make them about 10% out. The ADR's allow up to 10% on the speedo. The funny thing is the ADR for the odometer has a finer tolerance, so the odometer is more accurate than the speedo. Bikes are notorious for incorrect speed readings.

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Joel Now containing 100\% E-Wang

9,368 posts · joined Feb 2006 · 2 Dec 2008, 5:24 pm

#682677

out of over 8 speedos none of my dubs have ever had an inacurate speedo but thats only with the right rolling diameter tyres
worst they are out is no more than 1-2kms
the odometers on the otherhand....🙄 dont think ive seen one thats right

i think its cos there cable drive nothing really to go wrong
cars now are all electric- u can turn off ur ignition driving and the speedo stops working
bad voltage, dodgy sensors etc would give dicky readings

classic example, a mates fairmont crapped its alternator a few weeks ago,
he slowed down for a 60km/h speed camera and his speedo stayed on 110km/h 😂

1303Steve Scirocco Rare

8,650 posts · joined Aug 2002 · 2 Dec 2008, 6:18 pm

#682692

Hi

Thanks for the replies.

When my son was learning to drive we fitted a digital speedo to his L bug/1303 that runs of magnet on the front hub. Its setup via a menu using the tyre diameter, at 100kph on the GPS its only about 2 or 3 ks over, so I'm fairly happy with its accuracy.

While my son was on his Ls we would often get scowls from other learner drivers if we overtook them, as they probably thought we were speeding when in fact if they were paying attention they were under the speed limit.

I would rather have my speedo spot on and then if I get booked its my fault.

Steve

t2 stop taking life so serious

1,102 posts · joined Mar 2004 · 2 Dec 2008, 6:25 pm

#682694

GPS will be more accurate everytime , tyre wear will throw out your speedo reading.
i have a 2008 toyota hiace with a navman in it , the speedo reads 10 kph faster than the navman at 100kph , all the GPS has done is make me go faster ,that and i no longer look at maps

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rose doin it for d girls

2,036 posts · joined Dec 2004 · 2 Dec 2008, 6:28 pm

#682696

So your car reads that you have travelled more than what you have so you get your car serviced more eg. every 10k you do you have really only travelled 9k so every 100,000k you have really only travelled 90,000k so you miss out on 10,000ks of your warranty now I know why car companies do this. and it also gives you a false fuel economy reading when you work it out as well.

ratbug aka toddy101

439 posts · joined Jan 2003 · 2 Dec 2008, 6:56 pm

#682705

eraser wrote:yeah the subarus and some toyotas are out by 10kms on purpose, something to do with speeding prevention.

Yep, I have the same problem with my 08 model subaru, I mentioned it when i got it serviced, and yeah got a statement from subaru saying they meet the adrs and that they deliberately make them over read to get people to slow down. Load of nonsense. In fact, the car was a demo, when i found out it was way out, i had thoughts that they might have fiddled with the speedo to make it appear to get up to speed quicker.

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ratbug aka toddy101

439 posts · joined Jan 2003 · 2 Dec 2008, 6:59 pm

#682706

Ohh and apparently the new adr's, speedo must read between 0% and (+10%+6km/h). In other words they can't read slower, but can read 10% plus another 6km/h over (116km/h reading at 100km/h is acceptable)

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