Euro NCAP is a not for profit organisation funded by its own members and European governments. While manufacturers do not have to have their cars tested by Euro NCAP, around 90% of models are. This means Euro NCAP's verdicts have huge influence in swaying safety-minded car buyers' decisions.
The tests are widely welcomed by legislative and motoring organisations because basic governmental regulations would only require a legal car to score the equivalent of a one-star rating out of five to be acceptable for use on the road.
However, cars tested by Euro NCAP are awarded an overall rating out of five stars for their overall safety, as well as individual percentage scores for adult, child and pedestrian protection, with an additional score awarded for a variety of types of safety equipment and aids being fitted. This helps car buyers know which cars are safest.
Euro NCAP tests are widely credited for playing a key role in reducing the number of deaths or serious injuries from road accidents. The tests are frequently updated, and the criteria for achieving high scores regularly re-evaluated in order to ensure that safety advances are rewarded with higher rankings.
Euro NCAP scores are valid for six years, with manufacturers encouraged to have cars re-evaluated after this period, when they will be re-categorised according to any updates in the testing regime.
What Car?'s annual Safety Award - given in association with safety experts Thatcham Research, which works with Euro NCAP - is strongly influenced by Euro NCAP scores.
Euro NCAP criticisms
Euro NCAP's test methods have come under criticism, most specifically because the tests do not include an offset vehicle-to-vehicle impact test, simulating when two vehicles partially collide. These tests are conducted by other global safety testing authorities, including in the USA.
Euro NCAP counters that it focuses its tests - and budget - on the areas that have the greatest influence on the chance of death or serious injury.
The fact that Euro NCAP tests are conducted under laboratory conditions has also been criticised, because the nature of accidents means that they rarely unfold to the exact circumstances of the tests. In response, Euro NCAP highlights that consistent testing allows for comparable results from which consumers can make car-buying decisions, and adds that it would be impossible to replicate every accident situation.
Car manufacturers have also been accused of designing cars purely to achieve high Euro NCAP results. Euro NCAP says, however, that this should be encouraged, because the tests are chosen because they focus on the most important areas for preventing death or serious injury.
Euro NCAP test procedures
A wide range of front and side impact tests, plus whiplash tests, are carried out to evaluate the level of protection for adult drivers and passengers. Each is designed to assess the performance of a car in the event of an accident, using crash test dummies to record how well passengers are protected in variety of types of incident.
To simulate the most common form of fatal impact, a front-on crash, the so-called Offset-Deformable Barrier impact is used. In the test the car is driven at 39.7mph with 40% of its nose impacting into a deformable barrier, which is designed to simulate an oncoming vehicle.
The second most common form of fatal accident involves a side impact. To test a car's strength in a conventional side impact accident, a deformable barrier representing another car is driven at 31mph into the car's side, revealing how safe occupants are in both the front and rear seats.
Another common form of side impacting accident can involve a car sliding into a tree or lamp post-like object. To test this, Euro NCAP propels a car sideways at 20mph and impacts it into a solid pole. This test is often considered to be one of the hardest, because the full brunt of the impact is concentrated on such a small area of the vehicle.
Key safety features that have been introduced to production cars since the introduction of these side tests include seat-mounted and head-height side-impact airbags. The thickness of the pillars supporting the roof has also grown substantially to add protection.
Additionally, NCAP tests evaluate how effective a car's safety systems are at preventing whiplash injuries. Although these types of injuries are often not life-threatening, they are among the most common in an accident.
An increasing number of new cars are fitted with some form of automatic braking system, which uses sensors to monitor the road ahead and can automatically apply the brakes to avoid a potential accident. Euro NCAP assesses these systems in its tests to determine their effectiveness at a variety of speeds.
Euro NCAP also tests the level of child impact protection in its car crash evaluations, as well as giving marks for the compatibility of the car's fixings for child seat restraint systems such as ISOFIX and i-Size.
Euro NCAP also tests what level of pedestrian impact protection is on offer from the car if it hits someone. The latter tests have encouraged the use of softer bonnet materials and external airbags that can cushion an impact.
A recent addition to the Euro NCAP tests is the safety assist score, which focuses on autonomous features of a car such as adaptive cruise control and lane departure control and which can automatically avoid accidents by controlling the car for the driver. The Volvo XC90 - What Car?'s 2016 Safety Award winner - is an example of a car to score well in this area. It received a 100% rating.
Do the tests improve safety?
In short, What Car? believes the answer is yes.
Recent successes of the Euro NCAP tests include encouraging manufacturers to fit AEB automatic braking systems as standard, and succeeding in pushing manufacturers to fit standard electronic stability control, which can help prevent you losing control in slippery conditions. Looking further back, Euro NCAP has also played a key role in persuading car manufacturers to fit more airbags to to car interiors, and to improve child and pedestrian safety systems.
Got a motoring question? Our experts are standing by to help, just tweet us your question using #askwhatcar
For all the latest reviews, advice and new car deals, sign up to the What Car? newsletter here