Insurance Institute for Highway Safety
Not every model of car is tested. Both agencies test the most widely sold vehicles. Convertibles and other limited production cars are often not tested. In 2007 the IIHS did test 10 models. Test results often appear months after a car goes on sale. Both agencies buy their vehicles from car dealerships. The IIHS has only begun to mention upcoming (to be tested) models while the NHTSA has noted this for some time.