I have never smoked in that car, as I bought it a year after I quit. I haven't forced her not too, but the GF has only smoked it in twice. Both times when we were a bit stressed. Once going to see my mother in the hospital and we knew she didn't have long. She wanted to make sure I didn't drive like a looney The other was when she drove to the funeral and needed a smoke on the way back home.
Other than that, even when she borrowed it, she hasn't smoked in it. So a blitz with Fabreze across the headling and carpet once in a while, and a regular air freshener does the job.