Navigator take into account timezone for I don't know what reason to predict arrival time.
Time on device is allays OK because it synchronized with car.
Timezone by default is Chineese. I could set E.Evropean standart time in control panel.
However
1) This setting not stored persistly
2) What If I will travel around the Europe? I have to ajust timezone each time? I can just easily ajust car clock and that's it.