Car buying – safety features

If you're buying a new car there are lots of things to consider from looks and condition to performance and running costs. But don't forget safety. A test drive will help you check that the driving position, controls and all-round vision suit your needs and you will want to make sure it has the features you need to help protect your family in an accident.

Cars are not all the same. Newer cars will have more safety features and may offer better protection in a crash compared to an earlier model.

Car safety features fall into two categories, known as 'primary' and 'secondary' safety.

• Primary safety describes features designed to help you avoid a crash. Brakes and lights fall into this group as well as systems like electronic stability control or lane keeping support
• Secondary safety features come into play once you have an accident and are designed to reduce injuries to you and your passengers. This covers seat belts and airbags, head restraints and the design of the bodyshell and vehicle interior

Test drive – general checks

The basic mechanics of the vehicle like brakes, steering, lights and tyres must be in good order but there are other aspects of primary safety that you should check when you take a test drive.

• Can you adjust the seat and steering so you are comfortable?
• Can you reach all of the controls?
• Can you see the instruments clearly?
• Can you see all round the car? Do the windscreen pillars or head restraints block your view behind?
• Do the lights give you a clear view of the road ahead?
• Does the car feel right and do you feel in control?

An MOT only shows that the car was in working order on the day of the test. If it's got less than three months to run, ask the seller to arrange a new one.

A vehicle inspection will give you peace of mind about the vehicle's mechanical condition and operation.

Electronic safety systems

Anti-lock Brakes (ABS) helps you keep control of the car in an emergency and have been a standard feature of all new cars since 2004. ABS helps you maintain steering control under emergency braking.

Electronic Brake Assist senses how firmly you brake and if appropriate keeps applying the brake to help the ABS work. Some drivers back off the brake pedal once they feel the ABS kick in, reducing its effectiveness in an emergency.

Electronic Stability Control (ESC) detects differences between the car's course and your intended course. It can sense when you are about to lose control and can automatically apply braking to individual wheels to help you keep control.

Tyre pressure monitoring gives you early warning of a puncture. Most punctures involve slow air-loss and could go unnoticed in a modern car. Low tyre pressure will affect handling and braking in an emergency. Tyre pressure monitoring is essential where runflat tyres are fitted.

Injury prevention

Seatbelts have been around for over 30 years but the design hasn't stood still. Modern seatbelt provide improved protection thanks to:

• Pre-tensioners and grabbers that take up slack in the seat belt a split second after the crash starts
• Load limiters that stop the seatbelt pulling too hard on your chest
• Lap and diagonal seatbelts in the centre-rear seat instead of the simple static lap belt fitted for many years.

Air bags

Airbags are supplementary restraints – they give additional protection to someone wearing a seatbelt. It's not unusual to find six airbags in a modern car – three each for the driver and front-seat passenger.

• An airbag in the dashboard or steering wheel protects the head and chest in a frontal crash
• An airbag in the door or the side of the seat protects the chest, tummy and pelvis in a side impact.
• An airbag mounted in the edge of the roof over the doors protects the head in a side impact or roll-over accident.

We're now seeing the introduction of knee protecting airbags and bags for rear seat passengers too. Expect even more in the future.

It could be fatal for the child, and is now illegal, to use a rear facing child seat on a passenger seat equipped with an active frontal airbag. You'll need to look at cars that don't have a front-passenger airbag or cars where the passenger airbag can be switched off.

Crash tests

Full scale crash tests are the only reliable way of finding out how well airbags and seat belts can protect the car's occupants. They also show how well the car body is able to absorb crash energy without the passenger compartment being crushed.

The European New Car Assessment Programme (Euro NCAP) has been crash testing and rating new cars since 1997. Their tests will tell you:

• how the car performs in a front and side impact crash
• if the passenger compartment acts as a safety cage or crumples and collapses
• if airbags and seatbelts can protect people of different shapes and sizes
• if there is sufficient padding inside the car in areas you might strike in a crash

When Euro NCAP started they awarded two star ratings to each model tested – an adult occupant protection rating taking account of performance in frontal and side impact tests, and a pedestrian protection rating.

Since 2009 Euro NCAP has awarded a single, overall, safety rating up to a maximum of five stars. The new rating is made up from scores in four areas: adult occupant, child occupant, pedestrian protection and a new area, 'safety assist' which takes account of driver assistance and active safety systems.

(7 December 2011)