Car manufacturers love to tout safety ratings and crash prevention features to potential buyers, but have you ever wondered how car safety is measured?

There are two major organizations that perform car safety testing in the U.S., the Insurance Institute for Highway Safety (IIHS) and the National Highway Traffic Safety Administration (NHTSA). Both organizations review car safety features and perform crash tests on vehicles.

IIHS crash ratings

The IIHS was founded in 1959 by three major insurance associations and reinvented as an independent research organization in 1969. The IIHS tests focus on crashworthiness and crash avoidance and mitigation.

Crashworthiness ratings determine how well a vehicle protects the occupants in a collision. The IIHS uses six areas of the car including driver and passenger sides with small front overlap, moderate front overlap, sides, roof strength and head restraints.

Crash avoidance and mitigation tests examine how well a vehicle can detect and prevent a crash or lessen its severity. Crash avoidance tests focus on the avoidance systems in place, using performance tests to measure their effectiveness. Avoidance systems include driver warning systems and automatic braking. The headlight system is also tested.

NHTSA crash ratings

The NHTSA started in 1970 and began using a 5-Star Safety rating program starting in 1993. The 5-Star program evaluates how well vehicles perform in collisions and test vehicles in four different crash scenarios. The different scenarios are frontal crashes, side barrier crashes, side pole crashes and rollovers.

In each test a few things remain constant. A crash test dummy the size of an average adult male or female is used and the dummy is secured with a seat belt. Tests involving another vehicle use a similarly sized car that is within 250lbs. In rollover tests, the rollover resistance rating is based on the static stability factor (SSF) that measures how top heavy a vehicle is. Top heavy vehicles are more likely to tip over.

While a high safety rating is just one of things you will consider when thinking of purchasing a new car, you can review the safety ratings for any car on either the IIHS or the NHTSA websites by entering the make and model information.