http://mydeathspace.com/article/2007/12/14/Kanesha_Moise_(16)_was_killed_when_a_tractor_trail er_wheel_smashed_into_the_vehicle_she_was_riding_i n

A very similar thing happened to a friend of mine about 6 years ago.  He was in the car with his father on the freeway when a brake pad (or part of a brake system) from a truck came flying through their windshield.  It hit my friend square in the chest and he died. 

Freak accidents = terrifying.