CarPlay GPS issue

[MacMan988]

I recently bought a new car (Mercedes Benz CLA 180) and tried using Apple CarPlay in it. Everything else works except navigation apps. When I use either Google maps or Apple maps, the current location gets constantly switched between the actual current location and somewhere in the middle of the sea near Thailand every now and then. Even apps like Find iPhone also shows the same incorrect location when maps are showing the wrong location. All apps works fine when not using CarPlay.

I tested with two iPhone X devices (mine and my wife's) with iOS 12 and I see the same issue on both.
Tested with an iPhone 6s running iOS 11 and still the GPS issue is there.
Tested with Google Maps on Android Auto on my brother's phone and it works correctly!

Has anyone ever seen anything similar?

 

[Julien]

When you plug in the iPhone is using your car's GPS antenna/system. So it sounds like it is the problem. Does the 'stock' navigation work correctly?

 

[MacMan988]

When you plug in the iPhone is using your car's GPS antenna/system. So it sounds like it is the problem. Does the 'stock' navigation work correctly?

The car doesn't seems to have navigation.

But what's weird is that CarPlay/iOS gets both incorrect and correct locations from somewhere time to time. Maybe it is getting location updates from both built-in GPS antenna and car's antenna? If that is the case, still I wonder why would it receive an incorrect location from the car's system rather than not getting any location updates at all.