We had exactly the same problem with a used 97 Honda Accord wagon that we bought, c. 2000. Someone suggested Fabreze, so I bought a bottle and my son used it all on the interior of the car. After this the car smelled worse, a sickening combination of Fabreze perfume and old cigarette smoke. So I took it to a shop that did ionizing or ozone (whatever it was) treatment. One time didn't help, so they offered to do it again. A little better, but still didn't help.
Finally, I gave up and avoided the car whenever possible (my wife drove it); her nose is remarkably insensitive. After about five years, she graduated to another car, and I started to drive the Honda. By then the odors had dissipated to the point where I could drive it without gagging. Now I barely notice it.
So take heart! Let someone else drive the car, and after five years you'll not notice the problem.
Or just do what I should have done; sell the car to a smoker, and buy another one.