I quit almost 4 years ago, after smoking for more than 30 years. The car was always my weakness, because I started smoking as a way to pass the time on the 5 hour trip to and from college.
I was never a heavy smoker, less than a half a pack a day - sometimes a pack would last me a week. I was definitely a stress smoker and had quit on numerous occasions only to pick one up again under stress. The only thing that worked for me was (1) being ready and (2) Chantix. Most likely it was simply being ready, but the daily check-ins and accountability certainly helped. I can not stand the smell of smoke now and can't believe that I put my friends and family thru that. Good luck!!!