Plain old charcoal briquettes will get the smell out of the vehicle. Put 2-3 in a plastic bag, hit with a hammer to break up, then put the broken bits in a small plastic bowl or bowl made of foil, in vehicle. The charcoal will suck up the smell. Works great in the fridge-better than baking soda.
Wouldn’t replacing the headliner be the way to get rid of the smell since that is where the smoke mostly traveled?
For the car I would recommend an auto detailer or a fire restoration company. They should have an industrial ozone generator that they can use to do the job.
Of course that assumes the source of the problem is gone.
I would approach any deal to remove cigarette smoke with a “I will pay you if it works” approach. Some people they will never admit that the smell is totally gone, and I would have to believe that for their noses the smell still exists.
best possible solution:
Never buy a car that’s been smoked in before 
You must be speaking from the voice of experience and thanks for the tip.
It does make sense that charcoal briquettes would work because of their properties. It’s certainly much cheaper to try that than it is to replace a headliner, unless you can fish a used headliner out of a junkyard and put it in yourself.
bscar’s solution of avoiding a car that’s been smoked in’s a good one, but sometimes you get fooled, because car dealers selling used cars can disguise the smell temporarily. We ended up with one that way. And of course, sometimes, people successfully quit smoking and don’t want the memo every time they climb in their car.
What worked for us with the used car we bought was Fabreeze, sold in pump spray bottles in the laundry products aisle. You have to wipe down all the vinyl surfaces like the dash with it, and then spray everything, particularly everthing cloth, including the headliner, cloth seats front-and-back (I don’t know what you do if there’s leather), the UNDERside of cloth seats, the carpeting, and the carpeting in the trunk. Use half the bottle of Fabreeze spraying everything inside the car. Close the car up and leave it overnight. Open the car up to air it out. The smell will come back, much fainter. Repeat in four to seven days and the smell will be gone, or at least it was in the used car we bought.
Be advised, some people strongly dislike the perfumey smell of Fabreeze. The Fabreeze smell does dissipate within a week or so.
I’d say something almost the opposite. If you get a car that smells like smoke and you don’t really like it, just take up smoking. After a while you won’t notice and the problem is solved!
When it cost more to buy a pack/carton of cigarettes than a gallon/tank of gasoline, I’d be inclined to disagree.
Got A Minute? How About A Day, A Week, A Month, Six Months?
Use whatever cover-ups you’d like to mask the smell. You can try a shallow pan of vinegar left on the floor overnight or they sell little scented smelly plastic things that clip on your vent outlets. Ozium spray is supposed to actually eliminate the odor. Try some. A little spritz goes a long way.
I’ve done all of this and they all help, but what really works is to give it about 6 months and put up with the cover-ups until then. We had a smoker’s car that lost its odor after about half a year and it didn’t come back even in heat and humidity.
CSA