I didn't see this, and if I missed it, let me know...
If you are a passenger in someone's car, and you smoke, but they don't, DO NOT assume you can smoke in their car, even if their spouse smokes.
<DH smokes, I don't- however, he does not use my car enough for anyone to be able to tell that he smokes in my car. I have a cousin that does smoke, and will light up without asking if it's okay and gets offended if I ask her to put it out.>