Just had a thought. Maybe the car is what the girls saw that they shouldn't have. Maybe the perp(s) had parked the car along the roadside, gone into the woods to do their deed (cook dope, pick up dope, rape, murder, deposit a body, whatever...) and didn't count on two girls walking down the road and being able later to id the car. So the girls walk past where the car is, maybe looking at it curiously, maybe not, and on the walk back the perps are waiting in the bushes, ambush the girls and high tail it out of there. Course you would think if it was a meth lab the car would have been hidden but if it was a dope head in need of a quick fix or a serial rapist/murderer unable to control himself any better (read "in final stages of melt down") then they may have thought they could just leave the car quickly, do the deed, and get away without anyone seeing them or the car.