I just want to add my opinion about how she may have accepted a ride:
I've been to Myrtle Beach approximately 30 times in my life, from childhood through now, and I stayed at Bar Harbor during July 4th week in 2006. I have never been during Spring Break, but I have been to MB during many holidays and I have a pretty good idea of what Spring Break is like. That section of Ocean Boulevard is very congested each night, starting at dinner time and continuing on through the night. A lot of people, especially teens, cruise up and down that stretch, windows down, music playing, talking to others on the street or getting yelled at flirtatiously by people hanging out on their street view balconies (cheaper than ocean view). The heaviest action is a few blocks north of both hotels, but Bar Harbor is definitely still on that cruising route, particularly when traffic gets backed up.
It is common when walking that street to keep playing "leapfrog" with noticeable vehicles. The car may be stopped for a light, you walk past the car, banter back and forth, then the light turns green, the car then catches up with you and the driver yells at you again as he passes you, but then when the car stops for the next light you pass him again and talk to each other again, and on and on until one of you gets to where you are going. This is most noticeable for me during Black Bike Week, when there are very unique bikes or cars that I'll keep leapfrogging. In my younger (and single) days, the guys definitely offered me rides, and we were complete strangers. So I can see where the guy would flatter her a few times, offer the ride, if she refused a few times he might say, "Hey it's not like I'm gonna drive off with you--traffic sucks!" And then eventually she gives in. Maybe he "misses" her stop and says he's gonna go around the block to cut around traffic and then just keeps heading south. I have no problem believing that she could have been talked into the car innocently enough and then things unfortunately went wonky from there.