...while BBs bounce off, retaining most of their kinetic energy.
They found rings in the car metal. Should be enough energy to initiate a tiny fracture in tempered glass.
As a kid, I was once quite confident that BBs from my shot-out pistol would be harmless after bouncing off the street 60 feet away, so was not worried about the neighbor’s window about 100 feet away. My confidence was ill-founded.