How did princess grace die?

Injuries received in an automobile accident, the exact details that have not been fully elucidated. There is some evidence that the Princess, if driving the vehicle, may have suffered a stroke behind the wheel, precipitating the crash. Another angle has it Stephanie was driving the auto. There are plenty of unanswered questiions. It is known she did sustain heavy head injuried which required, for her viewing, that she be dressed in a Wig.