you definitely did not pay attention in your classroom shared_session then. I instruct for PBOC. The rule is car being passed stays on line. I have never heard anything about waving traffic by only one direction. In fact, I can literally replay in my head Pete Magnuson yelling "Cars being passed, hold your line!" Also, EVERY group has a rule that windows must be down. It's an insurance policy thing. Even when it's raining they have to be down.