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Discussion Starter · #1 ·
Well I bought my wife a model 2019 (made in nov 2018) Hyundai Kona!
The car is amazing, we never owned such a car before, our "newest" car before was 2008 - So this is a HUGH change for us.
Everything seems to be working amazing except for the ACC -
It turns on just fine and stops and goes when the traffic does BUT
When we were returning the car home after purchase i was driving in my car in front of my wife and she put on the ACC to keep the speed and distance between us
and she complained about the car not keeping up, it was keeping the speed (80 kmh) and even exceeding it a bit to keep up with me in front of her (i was using the cruise control on my car too set to 80) but I was steadily getting further and further away from her.
After 30 mins we switched and i got to try it and experienced the same - I set the ACC with 2 car lengths and positioned myself behind her car , she set the cruise control to 80 in front of me and just let it drive and slowly but surely i was lagging more and more behind until i had to press on the gas and go up to 100 for a few seconds just to cut the LONG distance that was created between us.
Has anyone experienced this before? Is this a fault/issue that needs to be fixed as a warranty issue?
Are we using the ACC wrong?
appreciate your insight!
 

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I’m no expert, but that sounds like it’s under reading speed, or your other car is over (& it could be a combination of both)
If you tried that again, but set the Kona to 90, I’m pretty sure it’d just follow at the set distance
 

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Discussion Starter · #3 ·
I’m no expert, but that sounds like it’s under reading speed, or your other car is over (& it could be a combination of both)
If you tried that again, but set the Kona to 90, I’m pretty sure it’d just follow at the set distance
Ill give it a try tomorrow and see if that works, if it does and i have to set the speed to higher than the legal speed i guess i should complain to the dealership about it and get it repaired under warranty?
 

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If I understand you, two cars each set to 80kph and one is going slightly slower than the other.

Speedometer speed is based on speed of wheel rotations so perhaps the car going faster has slightly larger wheels? That could simply be less tyre wear or it might be the faster car has higher pressure in the tyres.
 

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Discussion Starter · #5 ·
If I understand you, two cars each set to 80kph and one is going slightly slower than the other.

Speedometer speed is based on speed of wheel rotations so perhaps the car going faster has slightly larger wheels? That could simply be less tyre wear or it might be the faster car has higher pressure in the tyres.
Can it be something as simple as that? I mean even if there is a slight difference between the way each car reads the speed it shouldn't be so great that the newer car would be left behind by a BIG gap.
We also pass one of those "check your speed" signs along the way - Tomorrow i will set my speed to 80 and see what the sign says!
 

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I’m no expert, but that sounds like it’s under reading speed, or your other car is over (& it could be a combination of both)
If you tried that again, but set the Kona to 90, I’m pretty sure it’d just follow at the set distance
There's a fair bit of error in speedos. Even in lorries with calibrated limiters you find one crawling past another over a few miles.
Just think if you are walking at 2 mph how quickly you will get away from a static object.
Just bung the 'follower' up by 5 xph and it'll be fine.
 

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How about you try the same exercise but change the order of cars? My hypothesis will be that the car behind will always lag. No matter which one is behind! :unsure::geek:
 

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Can it be something as simple as that? I mean even if there is a slight difference between the way each car reads the speed it shouldn't be so great that the newer car would be left behind by a BIG gap.
We also pass one of those "check your speed" signs along the way - Tomorrow i will set my speed to 80 and see what the sign says!
The sign will probably say 73 or 74.

As the others have said, set it to 90, and the car will keep up, sometimes showing 80, sometimes 81 or maybe even 82.
 

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Response time of ACC will vary based on distance setting (two blocks is more than enough). I believe in the Kona you can also set ACC response time, but the sharpest setting kangaroos?
 

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I have never owned a vehicle with an accurate speedo, the common perception is that manufacturers are regulated to avoid under-reading, but achieve this in different ways. Some brands have the displayed speed digitally exaggerated by a fixed amount, my Kona (and the Leaf before it), showing exactly 4kph more than my Tomtom gps, or the roadside radar advisories. OTOH my Prius speedo suffers from scaling, and is 6kph high at 50, and 8kph high at an indicated 100!
Additionally, tyre tread wear results in up to 1.5% variation over the life of the tyre, increasingly under-reading.
So your speedo display is what it is, but unlikely to ever be either accurate OR faulty. It WILL be consistent, but if you must have accuracy, use a gps readout...
 

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Yes, it's the speedo. Totally normal. Use both your phone gps in both cars to compare and you'll find that they won't agree. Every car is like that.
 

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I've tested with GPStest Android app multiple times and found the error to be around 5 km/h at 90 km/h, so to get real 90, I always put the ACC to 95 and Kona holds it very steadily, be it uphill or downhill (I have noticed some slowing down by ACC in steep curves).
 

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Discussion Starter · #15 ·
Ok so i've some road testing with gps and road side speed signs and it appears that my kona is off by 7-8kph, so i have to put in 87 to get 80.
Thats seems a bit much to me and i honestly wonder if this is normal.
We got all this tech and cant stay within 2-3 kph deviation?
But from reading other comments its seems common?
And setting the speed to much higher than the speed limit can lead to a strong boost if the car infront of me turns off and my car has nothing stoping it.
 

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Ok so i've some road testing with gps and road side speed signs and it appears that my kona is off by 7-8kph, so i have to put in 87 to get 80.
Thats seems a bit much to me and i honestly wonder if this is normal.
We got all this tech and cant stay within 2-3 kph deviation?
But from reading other comments its seems common?
And setting the speed to much higher than the speed limit can lead to a strong boost if the car infront of me turns off and my car has nothing stoping it.
Did you check what the real speed is of the other car?

You can display GPS speed on the satnav in the Kona.

As for speed accuracy, that is normal -
For example, 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. See How accurate is my speedometer? | startrescue.co.uk for more.
 

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Mine is miles out.

Based on a calibrated GPS device (RaceLogic) my car reads the following;

Indicated Speed (Mph) True Speed (Mph)

24 20
33 30
44 40
54 50
65 60
74 70
86 80

I gave up at 80mph because it was all getting a bit silly.

The acceleration is incredibly linear though. It’s pulling just as hard at 70mph as it does at 20mph. It makes a 1990’s hot hatch look incredibly slow and I’d say it’s quicker than most petrol warm hatches across the board right now.
 

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Every car I've had (ICE and now EV) has over-read by 1 or 2 miles per hour at lower speeds, going up to 3 to 5 miles per hour at higher speeds.
 

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Mine is miles out.

Based on a calibrated GPS device (RaceLogic) my car reads the following;

Indicated Speed (Mph) True Speed (Mph)

24 20
33 30
44 40
54 50
65 60
74 70
86 80

I gave up at 80mph because it was all getting a bit silly.

The acceleration is incredibly linear though. It’s pulling just as hard at 70mph as it does at 20mph. It makes a 1990’s hot hatch look incredibly slow and I’d say it’s quicker than most petrol warm hatches across the board right now.
So it is within spec….
 
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