See, I would think that a local would be the last one to bring her body back there because he would know of many other better places in the general geographical area to dump her without being seen. No one in their right mind would return to this location where a dead body was located. Nor would they bring a dead body to this location if they could bring it somewhere else more easily. At least in my mind. Of course we could be talking about someone who was not in their right mind but even people who are not in their right mind don't want to spend the rest of their lives in jail
That is why I am saying the reason he would involve the vehicle is if he did not have the means on him to get rid of the DNA after she fought and his DNA was on her. And had to go get it. Even if what he was going to get was as small as a pack of matches, that he didn't have on foot . But, lived close enough to do it quickly.