drivetrain from your smoker.

In my experience the smoke and tar (or whatever that yellow crap is) gets embedded in the plastic and carpet and no amount of cleaning will remove it, especially a chain smoker. A car owned by a careful smoker who leaves the cig out the window, save only to inhale, will actually clear up enough to be manageable, but you will still occasionally catch whiffs of it years later.

Such was the case with my dad's old TJ Jeep. We even had the top off entire summers and armor-alled/scrubbed the plastic, cleaned the carpets, and did the air freshener trick. This was a "carefully" smoked in vehicle and we removed enough to be satisfied.

So, in a sense, there is a reason they are significantly cheaper, and that's because you can't (or it's economically infeasible) to get rid of it.

If another CBer has a magic cure, I'm all ears, I avoided a manual tranny BMW M3 as a potential project/commuter car for this very reason..