She was arrested for refusal to obey a lawful order -- meaning refusial to get out of the car.
She probably lit up the cigarrette to cover up the smell of marijuana.
Ah yes...the "what am I being arrested for" argument when the answer becomes "resisting arrest"
TROOPER: “Do you mind putting out your cigarette, please?”
BLAND: “I’m in my car. Why do I have to put out my cigarette?”
TROOPER: “Well, you can step out now
The now part means after she refused to put out the cigarette.