Story : Surprisingly little is known about the behavior of cars and drivers in uncontrolled, real-world accidents, despite rigorous testing in laboratory-controlled crashes. Now, a first-of-its-kind experiment aims to discover what really happens in a multi-vehicle pileup and how cars and driving could be made safer. In the second episode of this two-part special, forensic analysis is put to the test. Real-life crash scene investigations have very little data to work with, so are they accurate? And what can we learn about car safety when there is actual data to show exactly what happened?