I've considered smoking a pipe in the car, but I don't. I do a lot of in-city driving with lots of other unpredictable people. I'm a moderate driver, not a slow poke, but pretty temperate. But I tend to have a few channels going in my brain already. I work at staying deliberate and focussed, but I'm not as good as some drivers. Had a family member who had immense concentration and could drive very fast without every cutting anyone off, and always knowing where other vehicles were and where they would be, what I called NASCAR proficient. That's not me. So I might take my pipe along, but I don't smoke it in the car. I might smoke a cigar after lunch on a long road trip, to avoid drowsiness, but mostly, I don't smoke and drive.