I'm not sure any past attempts mean his story of Mollie on the road is true. He may have realized that following women/girls and flirting or telling them they're pretty was simply not working, so he viewed isolation and an abduction easier than trolling for a victim and luring them. Predators take the path of least resistance, and just grabbing her, or incapacitating her and taking off with her, might have been that preferred path.
I don't know if the head trauma happened in the abduction or later. I do know that he's charged in the first 1st degree and the affidavit states that the murder was premeditated. If there was ever a time to claim an accident, or an oops, or a consensual situation gone bad, or, to claim that he or she was confused, and she became hysterical and tripped and fell over the car, or whatever, it would be when police show up and say they think he did it. But he chose to talk about his driving circles and a jogging/chasing event and her supposed words to him, and her reach for her phone, and her running toward a direction that took her farther away from any potential help (if I'm understanding where she was). And then to lead them to her body. I could maybe buy some or all of the initial encounter story if he had admitted the rest of the crime, but I just don't know based on this story how much is factual. I would assume they have location data on Mollie in that area? And would that not continue when he drove off with her and got her to the intersection and then headed to the cornfield that he says was his next location?