Quote:
Originally Posted by jokinawa
It's not a take no responsibility thing though. They have a responsibility to make sure their vehicles comply with all laws where they are sold. Laws usually dictate that speedometers absolutely cannot read slower than actual speed so BMW and other manufacturers add speed to compensate.
Here is more on it.
https://www.thrillist.com/cars/your-...-japanese-cars
Can you just use whichever app makes you happiest? Technically, GPS-based speed calculation will always be more accurate than wheel rotation based due to the changes in tire size over time. However, when testing this earlier today, it appeared Waze was polling every couple of seconds so it was lagging behind the X7 Speedometer changes. For instance I was completely stopped and Waze said 5mph. I set cruise to 60 and as soon as my speedometer hit 60 Waze was at 50, more than the tolerance. It soon normalized, but still it was lagged.
What resolution would make you happy? Coding is not hard as you suggested earlier, it just takes research/practice. You can also pay a 3rd party to code it. BMW will not do it since it is a legal liability for them. |
This vehicle, and others like it, have everything they need (GPS, accelerometers, and software programmability) to allow them calibrate their own speedometer regardless of the wear / pressure / size / etc on the tires. They can even figure out what country they are in, so in theory they could accommodate local laws and regulations. If some country requires speedometers to read 5% over the true value, that would be easy to program while letting the rest of the world see the actual speed.
Absolutely, the GPS speed indication is going to have some lag to it, but that is easily accounted for with the help of the accelerometers to find times when the speed has stabilized enough to make a measurement.
Every car I've purchased in the past 12 years has been within 1 mph of numerous local roadside radar speed indicators. Even my 13 year old entry level Toyota Corolla with its analog speedo is only off by a constant 2 mph no matter how fast or slow I'm going.