Safety ratings explained

• 

  There are three crash tests: one frontal and two side. The most severe test, used by both Australian and Euro NCAP, is a 40 per cent offset crash into a deformable barrier.

• Making the starting line for the five-star challenge now means a vehicle must have ESP.
• ESP systems sense when a car is going out of control, then brake individual wheels - and also often cut engine power - to bring it back into line.
• There are now two parts to NCAP, the crash testing and pedestrian impact testing.

Earning a five-star NCAP safety rating is tough.

It takes three individual crash tests, although one is optional and only available to vehicles which are aiming for a five-star score.

But just making the starting line for the five-star challenge now means a vehicle must have ESP stability control. It's a life-saving piece of technology intended to help a driver avoid a crash, instead of giving protection during a smash.

ESP systems sense when a car is going out of control, then brake individual wheels - and also often cut engine power - to bring it back into line.

It's a system which is classified as 'active safety', because it actively works to avoid a crash, instead of the 'passive safety' systems such as airbags and seatbelts which are needed during a crash.

ANCAP now also includes a pedestrian protection safety rating, Euro NCAP assesses child occupant protection, and there is more to come...

But NCAP programs around the world have been focussed on passive safety since the 1990s because they are designs and systems which can be tested and rated in a crash test.

"There are two parts to NCAP, the crash testing and pedestrian impact testing," says Michael Case, chief engineer of the RACV and one of the leaders of the ANCAP program.

"There are basically three crash tests: one frontal and two side. The most severe test, used by both Australian and Euro NCAP, is a 40 per cent offset crash into a deformable barrier.

"The side impact is done with a Mobile Deformable Barrier, which goes in at 50km/h. Then there is an optional side impact test called the 'pole test'.

"That is a much more severe test and the impact speed is 29km/h."

Turning the individual results into a star rating is a question that is answered by combining the individual scores. With a few twists.

"The points are a little complicated," says Case.

"The offset frontal is scored out of 16, the MDB is also scored out of 16, and the optional pole test is all-or-nothing and worth 2 points. So that takes you to 35."

"Then there are points for seat belt reminders, one each for the front seats and one for the back."

So the maximum possible score is 36 points, with the points awarded on how close a vehicle gets to the perfect result.

"One star is 0-8.5 points, two stars is 8.5-16.5, three stars is 16.5-24.5, four stars is 24.5-32.5, and five stars is anything better than 32.5 out of 36," says Case.