APPLE INSIDER
An Apple Car could have displays embedded within any glass in the vehicle, with laminated glass sandwiching various other materials to block external light, emit its own light, or to display an image.
The assorted computer systems of modern vehicles are, for the most, still operated via a dedicated display. This screen is usually mounted in the dashboard or infotainment unit, and is very obviously a screen when it is turned off.The need for displays limits how a car could be designed if it needs to incorporate them, and the parts used to create them give little room for maneuver other than dictating their size and placement in a vehicle.
Source: APPLE INSIDER