It's a residential area, and out of the way for anyone going off the mountain (at least by using a road and not a cliff)... which makes me curious as to why she was over there.
It's residential enough that I'm curious as to why nobody heard anything. I know that the house across the street from where the vehicle left the road was vacant (at the time) because the family that lived there were getting a divorce, but someone should've heard something when the car went off the road because it's a populated area.
ADDED: If it were an accident, then MP would've been much better served to immediately notify LE the day she disappeared because if someone heard something, then it would've been much more likely for them to mentally connect the dots with a loud crash off the side of the mountain. Two days later, the whole thing could've slipped their mind.