Out of all our vehicles I will only smoke in one of them just because of the smell factor. Up until last summer before the wreck, I had an old truck as a daily driver I kept for that very reason.
Now I had no choice to drive something else everyday and no way was I quitting smoking cigars again. Can't say for sure this is 100% foolproof or not yet...but it helps. The BEST IMHO would be an ozone generator. However the downside would be, from what I have read, ozone will speed up the deterioration of fabric.
EDIT: I just got in my car, although the smell is hardly there, there is a faint bit of cigar noticeable and I really had to smell for it. It is nothing like it used to be before that is for sure. It was faint enough my wife didn't notice. So definitely not 100% but definitely an improvement.