iPhone X si iPhone 8 have problems with GPS, some of Apple's customers report that they are located incorrectly in applications, especially when moving at high speed. The problem seems to affect iPhone 8 more than iPhone X, and replacing the defective units at an Apple Store does not solve the problem, Apple being aware of its existence and trying to solve it.
iPhone X and iPhone 8 do not have a GPS much different than the iPhone 7 series, at least according to the existing information, but it seems that there are still quite big problems with the functionality. We are not talking about many models of iPhone X and iPhone 8 that are affected by this GPS problem, at least theoretically, because practically Apple has implemented a solution for the problem in iOS 11.1, so the problem is still big.
iPhone X and iPhone 8 have problems with GPS
iPhone X and iPhone 8 had the problem solved in some cases after installing iOS 11.1, but in other cases it was necessary to install iOS 11.2 to fix the GPS problem on the phones. Considering that iOS 11.2 is currently offered in beta version, it is quite clear that iPhone X and iPhone 8 units that do not have this version will have to wait at least one more month until it is released.
"On both Google Maps and Apple Maps, the gps doesn't seem to keep up. The apps start up fine but once I start driving the GPS becomes erratic and loses me. Both navigation apps can't seem to locate me unless I re-start the app over and over again."
The iPhone X that I own is not affected by such a problem, but neither is the iPhone 8, so I could not confirm its existence, although even Apple does it through iOS updates. If you have problems with the correct GPS location on iPhone X or iPhone 8, then you should know that iOS 11.2 is your only solution, for now, to solve the problem to a satisfactory extent.
"iPhone 8 Plus here - doesn't sound as bad as your experience, but accuracy is significantly worse than my iPhone 6, to the extent that it sometimes puts me on the wrong road while navigating. Last night (indoors) I watched it slowly drift 200 meters away over a couple of minutes."
