GPS doesn't work if you're in a tunnel, but the Tesla Model S has come up with a solution.
As YouTuber Bjørn Nyland progresses along a tunnel, the car's display shows him moving parallel to the road, but not actually on it—but it still displays his position relative to how far along he is on his journey. Once Nyland exits the tunnel, the arrow indicating his position snaps back into place with the return of GPS.
As Nyland explains, the car's software uses a technique to figure out where you are (the technical name for this is "dead reckoning"). It takes your previously known position and guesses your current spot using your wheel rotation and the angle of your steering wheel.