About this scene
Regular weekday car ride. She's in the passenger seat. They're stopped at a long red light when she says it out loud, the line that flips the whole encounter. He laughs once and complies. From that point on she's the one running everything. Her hand goes first, then she leans across the gear shift, and the rest of the drive home extends by twenty minutes because they take a long way back. She is the one who suggested pulling it out. She is also the one who finishes the job.
What to watch for
The agency is the whole story. She gives the order, sets the pace, and decides where to take it. Watch her left hand on the dashboard. It anchors her every time she leans further in. The car keeps moving the whole time. The traffic light cycles green during one of the more involved sections and she doesn't move. He has to nudge her once when the cars behind start honking. She finishes him in her mouth before they reach their actual destination.