Blow-up seatbelts that inflate in less than 40 milliseconds are found to offer better crash protection in rear car seats.
The blow-up belts, which combine the restraint of a seatbelt with the protective cushioning of an airbag, will be available from next year.
Car manufacturer Ford said that the seatbelts would inflate almost instantly in an accident to protect the fragile bones and vulnerable organs of a young child or grandparent sat in the back of its family cars.
The company announced its plans on Wednesday, at its research and technology centre in Aachen, Germany, where the 'air-belts' have been tested to ensure they comply with European Union safety legislation.
They will be available in Europe as an optional extra costing about 250 pounds in the new Ford Mondeo, which will be on sale from the middle of next year for about 17,000 pounds.
Most probably, the technology will soon be offered in Ford's other cars, but a spokesman said it would not share it with its rivals.
The firm's seatbelt engineer Joerg Doering said the seatbelts had been designed specifically for back-seat passengers, who do not have the protection of airbags.
He said that the aim was 'to reduce head, neck and chest injuries for rear-seat passengers, [who are] often children and older passengers who can be more vulnerable to such injuries'.
"In everyday use, the inflatable belts operate like conventional seatbelts and are safe and compatible with booster seats," the Daily Mail quoted Doering as saying.
"But in the event of an accident, the belt rapidly expands to disperse crash forces across a body area five times greater than that achieved by a conventional seatbelt.
"We've tested the system extensively using our entire crash test dummy family, and it offers extra protection over the standard rear seatbelt system," he said.
The inflatable seatbelts are activated when crash sensors dotted around the car detect a sudden impact accident.
Unlike airbags, which are typically activated with heat-generating chemical reactions, the new seatbelts are inflated with cold compressed gas from a cylinder housed below the rear seat.
This will prevent passengers from receiving burns.
A Ford spokesman said that the belt would fill up "in about the same amount of time it takes a car travelling at highway speed to cover a yard of distance".
The inflatable seatbelts have been offered in the US since late last year, in Ford's off-road Explorer.
The company said 40 percent of customers had chosen the option.