[M_a_t_t]

I don't have any answers, but to add to your observations. When on my motorcycle if you don't expect it semis can push me away from the wake (when traveling in opposite directions). I feel PU's and SUV's usually driving by. I don't ever remember feeling it from a car.

I have felt the same in my car as well. I can't say I've ever noticed it when I'm the one moving (equal and opposite reactions?). Even when I drive my van.