How safe is your car?

Safety sells. Whereas the Eighties were all about hot hatches and 0-60s, cars are now supposed to protect your health more than promote your image. Car makers' ads are full of arcane expressions to convince us of their piousness and their cars' protectiveness. So we've examined the most-promoted safety features. All are useful, but some are a great deal more so than others. The higher the star rating the more vital the feature.

Crumple zones/safety cages *****

All new cars have them, which is a major reason why they are much safer than old ones. New cars are designed to absorb as much of the impact in a crash as possible through their crumple zones - deformable structures at the nose and tail of the vehicle, which include engine bay and boot, front and rear wings and bumpers. The more rigid structure immediately around you, the safety cage, should fend off whatever nasty has penetrated the cushioning extremities of the car.

Generally, the newer the car the more effective its crumple zones, as hi-tech computer design has improved the art enormously. The advances are particularly notable in small cars: a new Fiat Punto, for instance, will be much more protective in a crash than a 10-year-old Fiat Uno, despite having similar dimensions.

Nonetheless, the bigger the car, usually the better. In a head-on accident, the heavier car's mass works to its advantage: the other car will decelerate more savagely. Plus: extra metal in front and behind means you've got more crumple zone than the guy in the little supermini. The strongest cars still tend to be German or Swedish. They've been besotted by safety longer than, say, the Italians or the Japanese. A second-hand Mercedes or Volkswagen, then, is likely to be safer than a second-hand Fiat or Nissan.

Anti-lock brakes ****

These greatly increase the driver's chance of avoiding an accident. Now fitted as standard to most luxury cars and increasingly offered as an option on cheaper cars.

An electronic brain ensures that the wheels never lock, no matter how hard you stamp on the brakes. This means you retain some steering control, and also that - in dry or wet weather - you'll stop in less distance. Mind you, anti-lock brakes, or ABS, can't defy the laws of physics: if the surface is really slippery you still won't stop.

Collapsible steering column ****

Essential if a manufacturer is to pass the mandatory 30mph head-on impact test. The steering columns in old cars tended to spear their drivers through the chest, whereas modern cars' columns collapse in severe impacts. Mind you, the steering wheel remains, and, unless it's cushioned by an air bag, remains one of the biggest killers in a crash.

Dual circuit brakes ****

Again, mandatory. All cars have two hydraulic brake circuits, which feeds the pressure that you've applied to the brake pedal through to all four brakes. If one fails you can still stop, even if you have to press harder.

Seat belts *****

Mandatory in all new cars sold here, both for front and rear seats. A three-point belt is better than a lap belt, as fitted to some older cars and in the middle of most rear seats. Recent Volvos, Saabs, BMWs and Renaults have three-point belts in the middle of the rear seat.

Pre-tensioners are increasingly common - they tighten the belt in an impact, compensating for the stretch in a belt's webbing. Vauxhall has made them standard in all its cars. They are worthwhile, although pre- tensioned belts often have longer anchorage stalks, which can make fitting child seats awkward.

Air bags ***

The latest safety buzz term, and increasingly fitted as standard to cars. Some cars have passenger airbags, too. The air bag is no more than a fabric cushion, folded inside the steering wheel (or, for the passenger, inside the dashboard where you'd expect to find a glovebox). In an accident, a small explosion instantly inflates the bag. Your head hits the bag rather than the steering wheel or the dashboard. Air bags also cushion your chest.

Air bags were developed partly because American states were unwilling to legislate for the compulsory wearing of seat belts (citing the same individual freedom that enables you to buy a gun in the Land of the Free). They're not as effective as seat belts, but worthwhile as an added protective measure.

Side impact bars **

Most crashes tend to involve the front or back of cars which is where the crumple zones, seat belts and air bags all come in useful. There is clearly less protection at your side - just a door between you and the Transit that's jumped the lights.

New cars, designed from the outset to have side impact bars, will offer more side protection than a car without them. But, owing to the sales advantage conferred by offering "side impact bars" in ads and brochures, some makers have retrofitted them to older models. In some cases, they're probably worse than useless.

Safety pedal box **

The latest safety aid, introduced on the new Vauxhall Vectra. As air bags and seat belts have increasingly protected the chest and head, so injuries to other parts of the body - especially legs - have increased. The most common type of leg or foot injury is inflicted by the pedals. In the new Vectra, the entire pedal assembly swings out of the way in a bad accident.