Depends on how bad the smoke smell is. You'd probably have to shampoo and scrub everything you could get to on the interior, then run an ozone in it for 12 hours.

If it was owned by a chain smoker for 20 years, there is probably enough in the vents, padding in the seats, etc. that you'll never get the smell out. You can probably make some headway if the smell isn't that bad.