Thread: [UX] GPS Speed Calibration for 64bit iGO Luna / NextGen

Thanks, that's interesting. It turns out that it is possible to match the speed with the car's speed through selection. Perhaps this will make it possible to estimate the arrival time at a given destination more accurately when a route is set. Is it enough just to synchronize the speed with the car? Cars have a speed measurement error; also, a non-standard tire or wheel size can affect the actual speed of the vehicle.

Thank you for your interest!
You are right that car speedometers are not perfectly accurate either. However, the purpose of this module is different — it corrects the discrepancy between the GPS speed and the car's odometer reading, which in our case was consistently around 8%.
This specific discrepancy is common in older vehicles and can be caused by tire wear, non-standard wheel size, or simply the GPS receiver's characteristics on a particular device.
It is important to note that the module does not interfere with the raw GPS data in any way. The GPS receiver continues to calculate and report speed exactly as before. What the module does is apply a visual multiplier to the displayed speed — the number you see on screen, and the threshold at which overspeed warnings are triggered. Think of it as adjusting the needle on an analog gauge without touching the engine — the underlying data remains untouched.
Regarding arrival time estimation — yes, this is an additional benefit. When the displayed speed matches the actual vehicle speed more closely, route calculations and ETA should be more accurate.
The module does not claim to achieve absolute speed accuracy. It simply provides the driver with a simple tool to adjust the displayed speed to match what they observe in real driving conditions. The default value of 108% is our specific case — each user should calibrate it individually for their vehicle and device.

One potential real problem. The speedometer is not linear in most cases.
For example, at 100 km/h, it can be wrong 3 km/h, and at 130 over 5 km/h.

If you want the ux to be complete and really precise, it should be possible to set these characteristic scenarios - zone 30, city (50/60), regional (80), motorway (100), highway (130) and and some custom value (left to the user)

Just a suggestion

Yes the car speedometer and gps speaks different languages
In most of the cases difference its between 3-8 km/h For example for vv crafter 2021 the gps and speedometer match at 80km/h above and bellow that speed dont match at all I know bcs i make a test and take a red light in germany where red light its only for to pay attention at speed
As the author said are to manny factors involved,and for this module the user must know exactly all car parameters But probably the module will be improved
If ,let say military devices can measure very accurate,why we cant? Its a matter of when ,not of if
And my opinion its the car speedometers show less than gps on purpouse

Simply - a matter of costs. Yes, show less with intention
But that's not the subject of this topic

P.S. Recently I drove my friend's car, an old Ford Galaxy, on a winter set, more than 1200 km and was shocked by the accuracy of its speedometer. Literally in a kilometer in the range of 60-140km/h

cristianyxtl
Your thinking is going in the right direction. Car speedometers are intentionally calibrated to show a slightly higher speed for safety reasons. That’s not really a problem, but I wanted the navigation I use to warn me in time when I’m exceeding the speed limit.
> In all the cars I’ve driven, the difference has been around 8%. That’s why I set this value as the default.

It’s great that the iGO app allows for such wonderful tinkering and experimentation.
However, the situation is this: my 2018 Renault Clio features a built-in "iGO" system—running on TomTom maps—that utilizes the vehicle's digital speedometer. This means that when my car's speedometer reads 33 km/h, the GPS registers my speed as 30 km/h; consequently, the factory-installed iGO system "complains" that I am speeding—something the Nextgen version on my smartphone, naturally, does not do.
Therefore, I choose not to "manipulate" the "unlocked" iGO version, as it provides me with a certain sense of security—ensuring I don't get caught out by speed traps or similar issues. Furthermore, ever since iGO 8.1, I have always relied on the app's time-of-arrival calculations; for years, I traveled happily in my motorhome using it—without ever feeling the need to tweak its settings.
Conclusion: Full credit goes to the effort put into this user experience—yet, for the life of me, I still don't understand the actual point behind it. 🤔🙄🤨

Nevertheless, I wish you continued joy and success in your programming 👍🤝🙋*♂️