However, it was said that the driver survived fine but that the girl who passed away (later after the accident from brain damage) was a rear seat passenger. The driver did state that the truck hit towards the rear of the side of the car. In light of what IIHS said about the rear passenger during a side impact crash (versus the driver side), the odds of surviving should be higher. Also see the above NHTSA numbers. Ironically, the driver survived and the rear passenger did not in this specific accident. The driver was "treated at the hospital and released." btw, there was mention by one of the Mercedes occupants (in a related link from that newspaper) that they heard the truck driver accelerate at the last minute as it ran into the rear side of the car.
The point being, that this accident occurred (all accidents are unique and tests can only replicate one specific accident used in testing), and accident investigators from both the insurance companies and MBUSA will determine the specifics in this case and what caused the injuries that led to the fatality. Again, all accidents are unique.
The W211 E Class has an acceptable rating from IIHS (and a good from NHTSA) for driver's side impact accidents. The driver may very well receive broken ribs and/or pelvis, and/or some internal injuries according to their test case. The rear passenger should fare pretty well according to their test case. In fact, there is a low risk. What caused the young rear passenger to receive injuries that were fatal to her? The investigators will determine that.
Not to mention that rear side-impact airbags are an option that this car may or may not be equipped with.