Motorists were urged to cut the number of whiplash injuries from more than 200,000 a year by taking just a few seconds to make a minor adjustment to their head restraints.

Almost three-quarters (72 per cent) of those who travel in the front seats of vehicles fail to position their head rests correctly, which leaves them vulnerable to injury in the event of an accident, according to results published by leading motor research centre Thatcham.

Experts who conducted extensive tests on more than 250 vehicles over a two-year period, found that 26 per cent of all the latest 2003 models failed to offer drivers and passengers alike adequate protection against whiplash.

Of those surveyed, 49 per cent were categorised as good, one in four as adequate, 14 per cent as marginal and 12 per cent poor.

Manufacturers are now being called on to improve the designs of head rests, and incorporate a locking system to ensure that they do not shift out of place in an impact.

Manufacturers whose models consistently rated well in tests carried out at Thatcham's Berkshire centre included Volvo and Saab.

Other manufacturers actively working on effective whiplash protection include Renault, Mercedes-Benz, Peugeot-Citroen, and Toyota.