I have never smoked, however the previous operator of my patrol car did. It's evident by the cigarette burns in the seats, carpets, and the melted plastic on the door.
I "Adamized" the car when I first got it, including a complete cleaning of the interior (I mean everything, carpets, floormats, headliner, etc). I still noticed a faint smell of cigarette smoke that I just couldn't get rid of. A friend suggested an idea and I thought I would share it with you.
I was fortunate enough to leave the car parked for 11 days straight (mini vacation). During that time I bought a large bag of charcoal. I split it into two smaller brown paper bags and placed one in the front and one in the back (the car is separated by a cage). I was thrilled when I returned from vacation to find that the car no longer smelled like cigarette smoke.
I'm not sure if it will last, but it worked for now.