Speedo Accuracy

[johnv Member Find all posts View Profile Close johnv]

How are the 150 owners that run a GPS finding the accuracy of the speedo?

When I think I'm doing 110 on the cars speedo, GPS is only showing 104kph. Still have factory tyres on. Pretty poor for technology these days I think.

Last vehicle, the 120 was spot on.

johnv

[LaoK User account deleted at own request. Find all posts View Profile Close LaoK]

Re: Speedo Accuracy

I don't get a speed display on the factory GPS. I do get to code in three speeds (residential, freeway, etc) for the GPS to use to calculate the time it will take for me to reach my destination. It needs me to tell it what speeds I will be doing on suburban roads or freeways.

I have only experienced the actual vehicle speed display on a TomTom running on a Pocket PC.

[Tezza222z Junior Member Find all posts View Profile Close Tezza222z]

Re: Speedo Accuracy

My speedo is out by 4kph at 100 by my GPS. Not bad, my landrover was out by 15.
Strangely the speed on my scanguage is spot on with the GPS, it must get its info from the engine electronics so why is the speedo wrong??
In answering my own question I suppose that the scanguage is getting an electrical signal from the motor whereas the speedo is getting a message from the gearbox or final drive.
So Toyota should run their speedo from the electrics.

[Dobbo Advanced Member Find all posts View Profile Close Dobbo]

Re: Speedo Accuracy

Yep, my speedo is about 4kms out at 100kph according to both my GPS and Scanguage.

[Gav&Jo Lurker Find all posts View Profile Close Gav&Jo]

Re: Speedo Accuracy

Hi guys,

Just drove from Brisbane to Rocky today (Sunday 30th January), so this is fresh in my mind. I replaced the standard tyres with Coopers ATRs and thought that the variation between speedo and GPS was due to the tyres. After reading other responses on this subject, it looks like I could be wrong!

At 100kph on the speedo, the GPS showed 94. At 110kph on the speedo, the GPS showed 106. Go figure!

At least it's better than the 120 series GXL I had previously. It was out by as much as 12 kph!! However every cloud has a silver lining!!! I've never told the wife about the adnormality in the speedo (as the speedo is always overstating the GPS speed) - so when she thinks she's speeding....she's most probably not. Easy on the bank balance!!!!

Gav

[Snowmann Junior Member Find all posts View Profile Close Snowmann]

Re: Speedo Accuracy

Hi Guys
My speedo is also optimistic compared to my Navman GPS. At 100kmh indicated on the speedo, the GPS indicates 94kmh. Still have standard tyres.
The GPS checks out almost exactly on my wife's Corolla - 100kmh on the speedo equalls 100kmh on the GPS so at least I know that the Prado speedo is more optimistic than the Corolla.
Mark

[andoland Senior Member Find all posts View Profile Close andoland]

Re: Speedo Accuracy

I have 265 70R17's on my GX, compared to the standard 245 0 R17's (which I think are only a mm or two smaller than the 265 65's that are standard on GXL's). Comparing the speedo to the GPS the speedo reads 1km/hr under at 100km/hr, i.e. GPS says 100km/hr, speedo says 99.

Ando

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

Re: Speedo Accuracy

Not sure when it started but sometime after 2005 when i bought my first prado with an accurate speedo, the law for new vehicles states that the speedo can read fast, but it is illegal for it to read slow. I have heard similar complaints from loads of people with new cars all saying that their speedos read fast.

The upside of this is when i fitted 265/70's to my current Prado it corrected the speedo so it is now spot on

Interestingly the Odometer reads correctly with standard tyres, so now i get an extra 5% of travel for the same odometer reading with the bigger tyres

Good all round for me.

Cheers Andrew

[dermie75 Member Find all posts View Profile Close dermie75]

Re: Speedo Accuracy

At 130km/h on the speedo, my gps shows 128 clicks. 150 Series GXL, 1600kms or so on the clock.

[gools Lurker Find all posts View Profile Close gools]

Re: Speedo Accuracy

Hi all,
We have the ZR and haven't seen the speed on the GPS screen, but I know if the speedo tells me I'm sitting on 100k/h, the average speed on the display in between taco and speedo tells me its 94k/h.???

[Jase150 Junior Member Find all posts View Profile Close Jase150]

Re: Speedo Accuracy

My speedo was intitially out by around 5% according to the Tom Tom 930, as soon as I fitted the Wrangler MTRs (265x70x17) it is absolutely spot on, unless of course I am travelling around a large sweeping bend when GPS's lose their accuracy in speed calculation.