Here's a question I haven't seen asked yet.
Who tells her friends she's going to look for a ride
without mentioning the names of the people she's going to ask?
Somebody on Facebook suggested that the LE -- and her friends and family -- know who she got a ride from. I think that theory explains pretty much every puzzling point debated over in these threads, from the conflicting information that was released about the car, to why her friends let her leave, to why she did leave instead of hanging around in her car, to why they haven't been looking at surveillance video, or doing extensive searches, to why her friends aren't talking. If this is the case, it makes sense still that what the LE want is an eyewitness who can place the known suspect, or his/her car, at the scene.
Where this theory confuses me is, in a case like this, don't they have the right to just go check out someone anyway? Or do they not know where he is, or do they fear for her safety if they release his ID? (Which would be great, in a perverse way, because that suggests they think she's still OK.) But if this theory is correct, seriously, how much longer can they try this approach? If somebody has slapped the theory up on Facebook, it's certainly not a secret anymore!
ETA: Actually, on extended thought, this theory would still not explain why they were so slow to look at the surveillance video.
And edited once again to add: Although this theory
could support the idea that she left, at least first, with the idea of running off for the night? A secret date gone bad?