These cars are rated by ANCAP, which use a range of tests that simulate how cars are likely to perform in a crash and the likely injuries a driver and passengers may receive in a crash. The ANCAP test results have shown 4 and 5-star cars offer greater protection in the event of a crash than 1, 2 or 3-star ANCAP rated vehicles.
It is important to remember that any vehicle safety rating system can only provide an indication of the relative levels of protection between vehicles you can expect in the event of a crash. A particular rating under a vehicle rating system provides a guide as to the relative safety of a vehicle model—it cannot, and does not, guarantee that a model of vehicle is safe, nor that a particular vehicle is safe. Whether a motorists or passenger is killed or seriously injured in a crash also depends on how safely you drive your vehicle.