A DUAL stage airbag which alters the rate of inflation to suit the force of a crash will make its debut on Volvo's new large estate model due to be revealed in January. The system uses a sensor that registers the force of an impact and adjusts the degree of inflation to suit, as well a co-ordinating it with the seatbelt restraint.

At the point of impact, the seatbelt tensioner tightens to hold the occupant in place and then releases to decelerate the body more gently into the airbag. It also senses if a seatbelt is being worn and determines the point at which the airbag is deployed and with what force. The new Volvo estate will also be fitted with a system that alerts emergency services if an airbag is deployed. It will be offered on the car as an option in America when it goes on sale next year.