As the oncoming air hits the wing and moves either over or under it, it speeds up and squeezes between the wing and the surrounding air. Many books state that air speeds up over a wing because it has further to travel than air moving under the wing. Air moving over the top of a wing speeds up so much that it arrives at point B sooner than air that travels beneath the wing. That tug is caused by air pressure. As the car and truck pass each other, they form a narrower space that forces air to speed up.
Air pressure drops between the car and truck.
The higher air pressure on the other side of the car pushes the car and the truck toward each other as they pass. 1996, National Air and Space Museum, Smithsonian Institution.