The sole occupant driver drove into a slightly elevated driveway and stopped. The driveway is maybe 5 degree incline. The shift select lever was placed in Park and the Driver visually confirmed it was in park. Driver sat in the car for 12 seconds before exiting the vehicle with the engine running and AC on. The driver exited and was standing outside of the vehicle with both feet on the ground for 6 seconds reaching back inside at which time the vehicle began to suddenly roll down the driveway causing injury to the driver. This seems to be a failure of the parking system of the vehicle causing serious injury to the driver. The vehicle has not been inspected yet and investigation is ongoing. It is unknown if there were any warning lamps, messages or other symptoms of the problem prior to the failure, but there was no prior service work performed on the near new vehicle. There is a video of the incident.