The Meaning of Vehicle Safety Ratings

Tuesday, January 15, 2013

All motorists have seen safety ratings like 3, 4 or 5 associated with their vehicles, but the meaning of these is not commonly understood. In other words, if they are meant to guide buyers towards buying the safer vehicles, they will fail miserably if not understood.

Another factor that needlessly complicates safety ratings is that no two testing organisations carry out the same tests. Consumers thus have to make sense of the ratings relative to the tests of the organisation that releases them.

As a result, it is impossible to give a general guide on what the numbers mean. But by overlooking the more technical differences and collecting the similarities, one can acquire some understanding of vehicle safety ratings.

The aim of safety ratings is to rank vehicles according to how safe they are and how well the occupants are protected during certain types of crashes. Organisations usually perform four types of tests:

  • They crash the car’s front into hard and soft obstacles at about 60-70 kilometres an hour and test the effects at various points on its body and the crash test dummies that occupy it.

  • They crash something that resembles the front-end of a SUV into the side of a vehicle at approximately 40-50 kmph and test the damage to the car and the dummies. This mostly tests the side airbags and body strength of the vehicle.

  • They drop a heavy plate onto the car’s roof at a carefully measured speed and test whether the roof caves in and whether the occupants are protected. This is to test cars for rollover accidents.

  • They strike a stationary car from behind at about 30 kmph and test the effect on the neck and back of the dummies. This is mostly a head rest and seat strength and stability test.

The Test Results:

  • The ratings range from one to five stars, with five stars being the safest and one star being the least safe.

  • The test scores are relative to the size of the vehicles. In other words, since a larger vehicle will necessarily provide better protection than a small one, a five star rating for a small vehicle does not mean that it is safer than a large vehicle with four stars.

  • The difference between the safety of vehicles along the continuum of ratings is large. That is, a five star rated vehicle is typically twice or three time safer than one with four stars.

  • Testing organisations build various additional features into their test results. Especially crash avoidance features have gained popularity. For example, for many organisations, electronic stability control (ESC) must be available in a car before it can be awarded a five star rating. This is because research demonstrates that ESC prevents 50% of accidents by helping drivers maintain control of their vehicles during emergency manoeuvres.

If potential buyers wish to know exactly what their preferred vehicle’s safety rating means, it is easy to visit some of the most common testing organisations’ websites. They can then compare their preferred vehicle’s ratings with other vehicles rated by the same organisation. This might eliminate the confusion associated with comparing different organisations’ ratings.