Removing cigarette/cigar smoke residue, ozone machine?

I have been in the car business for decades and removing smoke odors from used cars has always been a problem, but not as bad as it used to be when everyone smoked. Ozone treatment was the most effective along with hot water extraction cleaning of all soft trim inside the vehicle. In some cases, you could never get all the traces of tobacco smoke out without covering it up with other scents or chemical smells. Good luck you're on the right track with the ozone treatment.