Heads Up Display
I prototyped a heads-up display for a car windshield, using a Raspberry Pi and Arduino Mega. The visual interface was created in Python. I used a 7" LCD, reflected upwards toward the slanted glass windshield, to overlay the interface onto the driver's view.
Because of reflection inside the glass, the driver saw a double image of the display. Polarizing films or a semi-reflective coating on the inside of the windshield could solve this issue, but would be a safety hazard because of visibility concerns.