Have you ever been frustrated when smoking a cigar while driving? Is the main reason because the smoke is more distracting than the actual driving? Correctly opening the driver window with the right amount of gap near the top of the door frame is crucial to smoke evacuation while driving.
Depending on what type of car and whether the window is long as in a two door, or short, ..four door,,,has all to do with the airflow coming off the windshield and over the door frame. Also, using the A/C, or just the blower fan in the vehicle to bring in positive pressure air, especially setting it to blow from the floor area, because blowing from the middle dash vents will push the smoke into your eyes, this will help carry the cigar smoke up to the window top and the negative pressure zone outside the window at the top usually gets the smoke out smoothly without too much issue.
I purchased a vent visor specifically for this reason to increase the negative pressure zone, and to keep rain out during , what else, Rain. And another tip is when I have to stop at a store quickly, I leave my cigar on the outside of the car wedged between the windshield wiper arm and blade facing ash up, so as not to burn a hole in my seats or carpets in case it falls over. Because most new cars do not come with ashtrays today, that is actually an option for most cars. But please be responsible and not throw the finished cigar out the window, that's just bad karma. I use an old steel travel mug with lid and dispose of at home.