Detachable Headrest
While this isn't the case for all cars, most have completely removable headrests. It's an accomodation for tall people but also a safety feature. If someone is stuck inside the car, they can remove the headrest and use the metal prongs to break the window.
Cream Tube Cap
There's a small cone-like shape on most medicated cream caps and toothpastes for a convenience reason. Instead of struggling to pull off that tight foil seal, use the cone to poke a hole in the foil for easy access.