having been a smoker in the past and experienced smoking whilst driving, i can think of no reason to ban it.
it does NOT follow the same logic as mobile phones, as the "evidence" that brought in the mobile phone ban is to do with your lack of concentration whlst having a conversation, not havng your hand off the wheel (which makes the mobile ban completely unjustifyable imho as youre allowing handsfree?)
there is the risk of IDIOTS who cant cope with smoking/driving, but frankly these are the people who cause a danger just being NEAR a car, let alone smoking in one. If you have the inteligence to string together a full sentance, you should be able to hold a cigarette without dropping it.
As for fag ends out windows, it IS an offence, and you can be stopped/fined for it. it's just very difficult to enforce