I appreciated the tip regarding driving in the left lane while transporting anyone (see vehicular ambush preparedness). However, being shot at while driving hopefully will not occur as often as pedestrian-thrown objects entering the vehicle through open windows. Whether a lit cigarette butt or an unknown liquid, the consequences of scrambling out of the way can adversely affect the safety of the driver and whatever mission is being performed.
Always keep the passenger windows closed, and keep the driver’s window closed as much as possible. Vehicle air conditioners are great! Use them not just when transporting, but also when driving slowly through urban areas where there is a lot of foot traffic.