Neither my wife or I smoke and no one has ever smoked in our car. On separate occasions, both of us have smelled cigarette smoke in the car.
We have a 2006 Ford Taurus with 78k miles. We purchased the car as a program car from the original dealership with 22k miles.
Do you smell it when you turn your heater on? If yes, you might be mistaking the smell of hot antifreeze from the heater core for cigarette smell. It could also be mold buildup in the ductwork for the heater and A/C.