Other sections in this guide
- Overview
- Car safety features explained
- Primary safety explained
- Secondary safety explained
- Top five tips for buying a safe car
Car safety and child seats Primary safety explained
Primary safety features
The list of features to choose from when buying a car is long - and growing, as more makers focus attention on selling 'safety' as a benefit of buying their car. Here, we explain what 'primary' safety features are and highlight the main ones available.
1. Electronic stability control (ESC)
This electronic system can stop drivers from losing control of their car in sudden manoeuvres or skids, and independent studies have shown it could prevent up to a third of all road accidents. This car safety feature is commonly known as ESC, but other acronyms used by manufacturers include: ASC, DSC, DTSC, ESP, ESP+, VDC, VSA and VSC.
We test every car to see how well it performs in an emergency avoidance manoeuvre. When we compared two cars of the same design, the Citroën Nemo and the Fiat Qubo, the two cars performed very differently because the Citroën wasn't fitted with ESC. Watch our test video to see the shocking results.
2. Electronic brake-force distribution (EBD)
This enhancement of anti-lock brakes (ABS) reduces brake force if grip differs at each wheel, helping to bring the car to a halt predictably and in a straight line.
3. Lane-keeping technology
Some lane-keeping systems simply warn the driver if he lets the car stray from one motorway lane into another without indicating. Citroën's Lane Departure Warning System vibrates the base of the driver’s seat, and the system in the latest Ford Focus vibrates the steering wheel.
Some systems (like Honda’s Lane Keep Assist System on the Accord and Legend) automatically make steering adjustments to keep you in the centre of the lane. The most advanced systems (like that used by Mercedes) sense that you are going off-course and correct your direction by applying the brakes on the left or right wheels - in the same way the electronic stability control would if it sensed a skid situation.
4. Speed-limiting devices
Makers have offered cruise control features, which hold the car at a speed set by the driver, for many years. Now several manufacturers have adapted this system to provide a means of setting the maximum speed of the car. You can use it anywhere, at any speed setting you choose, but essentially it prevents you from inadvertently going over that speed, whether it's a speed limit or just a chosen 'safe' speed.
5. Smart seatbelt reminder
As a nation we’re pretty good at buckling up, but not using seatbelts is still a major factor in road traffic injury statistics. The best systems (such as those in the Volvo S40) don’t just remind the driver to buckle up, they sense which seats are occupied and alert the driver if any other belts haven’t been fastened.
6. Good visibility and/or visibility aids
You might hope 'good all-round visibility' would be among the first aims in any new car design. Unfortunately, with modern cars, there is always a conflict between the need to strengthen the cabin to withstand serious crashes and the need to see out from the driver's seat. This means that modern cars tend to have poorer visibility than older designs.
Warning when a car is in your blind spot
Where the visibility is compromised, many manufacturers now offer electronic sensing devices and even cameras to tell you when you're close to other objects. Basic systems include reverse parking sensors, used for low-speed manoeuvres to prevent the unseen extremities of the rear bumper from hitting other objects. At the other extreme, companies like BMW offer very sophisticated systems to warn you if there's a car driving in your car's blind-spot, or to pick out pedestrians on an unlit road by using infra-red cameras.
7. Adaptive cruise control
This uses cruise control to set the vehicle speed, but with the addition of automatic braking. Radar or laser sensors monitor the road in front and automatically apply the brakes to maintain a driver-pre-set distance between you and the car in front.
8. Attention monitoring systems
These systems monitor the driver's behaviour, looking for signs that might indicate tiredness. The systems vary in the responses they offer - with some sounding an alarm, others vibrating the seat and some setting off audible and visual warnings to alert the driver that it is time to take a break.
9. Active headlight systems
Basic active headlight systems have additional lights that come on to the left or right for cornering, lighting up the bend as you go. More sophisticated systems have active beam control - linking the direction of the headlamp beam directly to the steering. And the latest 'Intelligent Light System' from Mercedes, not only allows the headlamps to turn as the wheels do, but uses cameras to monitor the road for both cars in front and oncoming vehicles. If it senses them, it adjusts the headlight beam automatically, so as not to dazzle other drivers. As soon as the hazard is passed, the system re-activates full beam.
10. Automatic braking systems
These are advanced braking systems that use cameras, radars and automatic braking to prevent or lessen a collision before it happens. We've tested systems from Audi, BMW, Infiniti, Mercedes, Volkswagen and Volvo. Check out our auto-braking systems test results to see how well each system performed.
11. Tyre-Pressure Monitoring Systems
Having under- or over-inflated tyres can upset the car's handling and lead to an accident. Tyre-pressure monitoring systems (TPMS) are designed to monitor your tyre pressures, helping you maintain them at the correct pressures. There are two basic types - 'direct' and 'indirect' pressure monitoring.
Direct tyre pressure monitoring involves the use of a sensor inside each tyre to measure the pressure and send a signal to the car's onboard computer, so it can either display the pressure or simply activate a warning to say it is incorrect.
Indirect tyre pressure monitoring systems do not have sensors. Instead they use the anti-lock brake system (ABS) sensors to monitor wheel speed. If the system senses a change in a wheel speed relative to the other wheels, it calculates that the rolling circumference must have changed and assumes this is due to a change in tyre pressure.
System demonstration
Follow the link to see the advanced safety systems we've tested and how they compare. We were actively involved from the beginning as founding partners in Euro NCAP and we've been campaigning for improved primary and secondary safety systems for even longer than that. We've also been calling for stability control to be standard on all cars for several years.
Please enable JavaScript to access this content.
When it comes to primary safety, we checked out one of the market leaders - Mercedes - which demonstrated some of its most advanced primary safety systems using a simulator.
