Soften the blow and survive: Airbags that inflate to cushion motorists in crashes are being increasingly offered as optional extras. Roger Bell looks at the future of car safety

When two American cars collided head-on at a combined speed of more than 60mph, their drivers - both women - made history: they lived. They survived what would normally have been a fatal accident because airbags protected them from lethal impact against the steering wheel.

Airbags are not new, and they do not contain air. They are common in the United States where it is mandatory for all new cars to be fitted with some form of passive restraint - either an airbag or straps. In Britain, the compulsory use of seat belts (which are actually worn by 95 per cent of drivers) has stood in the way of moves towards expensive airbags, but although the lap-and-diagonal belt is an effective restraint, a supplementary air cushion gives even better protection.

Your next car could have one. Initiatives in Germany, where speeds are high and the safety lobby strong, lie behind the escalating use of airbags in Europe. Professor Ulrich Seiffert, head of research and development at Volkswagen, believes that airbags could help to make cars statistically safer to travel in than trains.

Airbags of the present generation are not the answer to all potentially fatal accidents. They are of little or no use if the car rolls over, for example, or in the event of tail-end or side impacts. They can be remarkably effective, however, when the victims are thrown forward violently - which occurs in about half the number of fatal accidents. In a head-on smash the airbag can make the difference between life and death, between minor injury and serious disfigurement. Accident analysis by Mercedes-Benz indicates that they reduce severe chest injuries to belted drivers by 25 per cent. Disregarding what it terms high-speed 'disaster' cases, the company claims that no one cushioned by a Mercedes airbag has suffered from severe head or facial injury.

Behind the simple idea of air-cushion protection, rooted in the aerospace industry but pioneered by Mercedes, is some highly sophisticated technology. On impact, sensors detect catastrophic deceleration and signal the detonation of a pyrotechnic charge. This instantly inflates (mainly with harmless nitrogen) a tightly folded nylon 'pillow' which bursts from a lidded recess usually in the boss of the steering wheel.

Instead of hitting a hard, unyielding steering wheel or facia, the occupant's chest and head - travelling forward at undiminished speed - is cushioned by a balloon. The airbag deflates (the gas escapes through holes in the fabric) almost as rapidly and the whole sequence is over in the blink of an eye, leaving victims bemused and probably in shock, but alive. Fears that a rapidly inflating airbag might have disastrous side-effects (perforating ear-drums or smashing spectacles, for instance) have proved largely groundless.

Misgivings about accidental release have also dissolved as a result of technical safeguards which ensure that the system's 'brain' can distinguish between a real crash and, say, the biff of a panel-beater's hammer.

There are basically two sorts of airbag. Those used in the US to meet federal requirements are big enough to cushion the whole body of a driver - who at best may be wearing a lap strap, but probably is not (only half of America's drivers do). But even in the US, the 'federal' airbag is intended as a 'supplementary restraint system', not a primary one. The smaller European bag is only designed to provide additional head protection once the lap-and-diagonal seat belt has restrained the torso. Although the European bag has its critics (the cost savings, some people say, do not justify its inferiority to the US version), it looks set to become commonplace without legislation.

Most new cars in the US now have airbags. In Britain today only a few expensive luxury imports have an airbag fitted as standard, though Jaguar has just announced that from 1993 all models will have airbags on the driver's side fitted as standard. Mercedes-Benz, which has offered airbags to customers in the United Kingdom since 1984, fits a federal version as standard to its S-class, SL and 500E models. The 600SEL has one for the passenger as well. Airbags are also standard on several Hondas (among them the NSX, Legend, Prelude 2.2 and Civic VEi), the BMW 850, Nissan Maxima SE and Mitsubishi 3000GT.

Several manufacturers now list airbags as extras. Mercedes does so on all its other models for pounds 750 a side (the price was halved last year to encourage sales). BMW charges a little less but cannot yet cushion-protect the front passenger in right-hand-drive cars.

Safety-conscious Volvo offers airbags on all its models, although it concedes that few buyers pay pounds 700 extra to have one. 'Most would sooner have a sunroof,' says a spokesman. Saab's optional federal airbag for the 9000 range (it is standard on the flagship Griffin) costs pounds 595.

Rover offers a federal driver's airbag for pounds 725 on its 800s. Smaller 200 and 400 siblings will get European bags next year. Even the Mini could be equipped by the mid-Nineties. Vauxhall will make airbags available for the Astra, Cavalier and Calibra next year. VW pledges the same for the Golf, Jetta and Passat. Ford says it will follow suit on some 1993 models.

Despite consumer apathy, airbag protection is likely to become optional on most new cars within the next two or three years and standard on many. Side-impact bags, which present a far greater technical challenge, are also on the way. The problem facing the industry is getting people to pay heavily for a lifesaver they may never see or use.

(Photograph omitted)