Same goes with a car. He could order her out of the car and if she brought the ciggy with her then he can tell her what to do with it on the grounds the scary girl might burn him with the ciggy, however being that smoking while in a car is not against the law he can ask but ordering and her saying no is the same as saying no to a search.
Cars are different under the law. When the window is open, smells of alcohol and drugs can provide cause for warrant searches. Cars are on a public roadway so ‘privacy of the home’ laws do not apply.
Smoking isn’t against the law in the car, but can interfere with his duties so he has the authority to order her to put it out.