The rating includes Silverado and Sierra 1500 Series Regular Cab, Extended Cab and Crew Cab pickup trucks, with or without optional head curtain side air bags. Both trucks also received a five star rating in frontal crash tests.
The NHTSA's side impact studies are accomplished by ramming an object into the driver's side of a vehicle at about 38 mph. There's a dummy in the driver's seat and another in a rear passenger seat, if the vehicle has one. Dummies are examined after the crash to determine how extensive their "injuries" are. It's not a perfect test, but helps us compare safety qualities among a set of similar vehicles.
The Insurance Institute for Highway Safety performs its own tests, but the object that hits the test vehicle moves at a slower speed and sits about a foot taller than the the NHTSA's version -- to better represent tall SUVs.
