Speedo on new car inaccurate

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glang, Oct 20, 12:23pm
Bought my Kia Seltos new earlier this year and always suspected the speedo was optimistic.
This weekend I checked the speedo against my old GPS unit which also displays speed and at 100kmph the Kia digital speedo was reading 105. At 50kmph the speedo reading was 54.
So presumably my car is clocking up more kms than actually travelled and so my fuel use reading is also inaccurate.
The car is still under warranty, is it possible to recalibrate the speedo at my next service, or do I have to live with it.

kazbanz, Oct 20, 12:25pm
totally normal.

hazelnut2, Oct 20, 12:27pm
I was told by my new Mazda provider that all the new cars produced now are actually moving at a few kilometers slower than what they read out. The speed law in NZ will soon permanently, all year long, change to ZERO tolerance over the speed limits, 100, 80, 70 50, etc, so it's a good thing to travel by what your car says and avoid speeding tickets!

There are ocassionally km calibration sections on highways. check against one of those to see if the km's match. It's all done by computer nowadays anyway so it's possible the km's are correct despite the speed being hobbled. I know our 'fuel to empty' readout isn't quite true as we can go a lot further than what it indicates.

bigfatmat1, Oct 20, 12:36pm
Its a adr requirement that speedo must read higher. The actual odo is not affected its a design feature

andrewcg53, Oct 20, 12:36pm
Have you fitted different sized tyres to your car or the dealer from the factory tyres say from 16 inch to 17 inch

glang, Oct 20, 12:43pm
No, car is completely standard with factory fitted wheels and tyres.

lk104, Oct 20, 12:43pm
As above, totally normal, all vehicle manufacturers have the same, always read approx. 10% over actual.

lythande1, Oct 20, 2:21pm
Mine is the same. a 2006 car. I'm used to it now, I drive at $105/55 according to my speedo and know I'm right at that.
Never bothered to fuss about it.
Tyres can do it sometimes, if you have the wrong size (had that once with an old classic) but my tyres are right so the speedo is just out a bit. which is not uncommon actually. Google it.

gammoner, Oct 20, 2:29pm
Problem is for the Diesel's, your paying RUC on Kms recorded but not travelled

franc123, Oct 20, 3:01pm
Read #4.

gsimpson, Oct 20, 3:43pm
It is a rather stupid idea. It normalises people to the speedo over reading so defeats the purpose. One should be given the correct speed.
All my old vehicles read spot on so it can be done.

s_nz, Oct 20, 3:51pm
As per #4 the speedo read out is inflated, and the ODO is typically pretty accurate. If you want to check the ODO's accuracy do so via distance not speed (If you are in Auckland there are signs on the southern motorway out of the city to assist with this).

I had a scangauge plugged into my car for a while and the speed reported via the OBDII port is significantly lower than what is displayed on the dash.

Regulations requre car speedo's to not under-read, and to overead by a maximum of something like 9km/k at 100km/h.

Despite being able to make fairly accurate speedo's, Automakers often chose to have them read quite high for the following reasons:
- Owner will likely drive slower, and hence the car will be more efficient, and the owner will hopefully be impressed by fuel economy.
- Car will be quieter at a given indicated travel speed.
- Car will accelerate quicker to given indicated speed, hence seem faster.
etc.

gpg58, Oct 20, 3:52pm
My 2013 navara was 10kph out at 100, until i fitted bigger tyres, so now is only 4-5kph out. I did check mileage reading when it was still new, also thinking about road tax, but as others say it seems that is accurate. In its case it cannot be fixed. - except by physically moving the needle position so its right at 100, but it then would read too slow at lower speeds. so decided to just put up with it, and use gps any time it mattered, until i actually marked the dial with twink, for correct position for usual limits.
My 2020 holden spark is 5 kph out, and my 2020 astra rsv is 4 kph out at any speed, so much easier than the navaras varing amount, as i can just drive that amount faster everywhere.
So agree, dam stupid idea by some dimwitted plonker, that achieves nothing, and pisses off traffic behind you, if you think its correct and stick to what it is reading.

curlcrown, Oct 20, 4:23pm
Any measurement without knowledge of it's uncertainty is meaningless.

nice_lady, Oct 20, 4:40pm
It's all to do with lawyers and companies trying to avoid getting sued by customers who got speeding tickets.

andyb2, Oct 20, 4:48pm
My sportage reads exactly as op when comparing to the smily or frowny face on the electronic signs.

tony9, Oct 20, 4:56pm
International standard for vehicle speedometer accuracy is from -0Km/Hr to +4Km/Hr+10% of actual speed.

tony9, Oct 20, 4:58pm
Already here now, there is now no tolerance over the posted speed limit.

tweake, Oct 20, 5:53pm
a lot of them now make the speedo a mile out, especially at higher speed, to make the driver drive slower therefore more economical which is a big selling point these days. ie its a dirty trick to gain more sales.

also it pays to watch that many speedo are 10 km out at 100kph but only 1km at 50kmh. ie its not the same % across the speed range. modern electronics can make it display whatever speed they like when they like.

stevo2, Oct 20, 5:55pm
Our 3 vehicles are all out from 4kph to 7kph according to 2 GPS's.
Odometer is spot on with all 3.

marte, Oct 20, 6:07pm

gamefisher, Oct 20, 6:17pm

gsimpson, Oct 20, 6:44pm
You would think then that manufacturers would make it simple to recalibrate the speedo. One can do the clutch etc. Why not the speedo?

tweake, Oct 20, 8:00pm
then people will play with it and manufactures get blamed for fines and gas guzzling cars.
its like why do they have idiot temp gauges that always show the same temp. because people are idiots and complain about normal ups and downs of temp.

dublo, Oct 20, 8:28pm
I recall driving the measured 8 km near Invercargill a couple of years ago, in a rental Tiida, at a steady indicated 100 km/h. Actual speed worked out to be about 92 km/h! The odometer also did not match up.

Bought an automatic, low km Triumph 2500 in 2002. My wife noted she had to drive our 2000 at about 105 km/h or more to keep up with me on the way home.
Later, on one of our first open-road drives in the car, just over the top of a rise it crept up to 107 km/h before I shut off power. The traffic cop parked there waiting for speeders turned on all his flashing lights and stopped me - 112 km/h, so I had to pay a "road user tax." Checked it on the 5 measured km section near home and sure enough, speedo reading low. Later I fitted a 2500S tachometer which also showed up the discrepancy. (Note that the tyres fitted to the car were the correct 185/80R13 size.) Eventually I converted it from automatic to manual/overdrive. With the correct speedo cable drive gear in the overdrive it is spot on! At 3050rpm in 4th and 2450 in overdrive it shows exactly 100 km/h.
I like to know that an instrument can be relied upon for its accuracy. And our modern Accord (well, a 1999 model) reads only about 2.5 km/h high.