He could have casually asked her "..hey I just dropped my phone (gestures to her footwell area)- can you reach it?" and then hit her on the head or stun gunned her? Also she would have been bent over and out of camera frame?
I was thinking along these lines too, but I have to admit I'm having trouble believing that she got in, he put his foot on the gas, "drops" his phone, asks her to pick it up, her complying, and him finding a way to incapacitate her all in.. what was it? 9 seconds? The quick timing is key here, IMO.
I don't think he used trickery to subdue her, I think as soon as she got in the car and the door closed he felt like he won, and he wasn't going to wait much longer to ensure he could have his "prize". MOO
I'm also having trouble subscribing to the idea he put the passenger side seat down when she got in, although perhaps that would be what caused her to panic. I just don't think that would accomplish his mission to have her out of sight, as she could have sat up, reached the back door (possibly) from laying back etc.
iMO she was rendered unconscious very very very quickly.
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