Thatcham has praised Volvo and Saab for their efforts in preventing whiplash but criticised many other car manufacturers for not doing enough.
This is mixed news for motor insurance companies, who have to pay out millions of pounds each year in whiplash injury compensation.
Woman's car insurance companies will be paying particular attention to these findings since ladies are significantly more likely to suffer from the injury than men.
In tests carried out by Thatcham, just 16% of the cars which were tested ranked as having 'good' whiplash protection whilst 36% were rated as being 'poor'.
It said: "Many manufacturers introduced designs that attempted to reduce whiplash injuries but the test showed many simply do not work."
Some of the cars that scored badly in the whiplash tests did well in other areas of injury protection carried out by Euro NCAP, such as the BMW X5, Citroen C4, Lexus GS and Peugeot 1007.
Lee-Anne Bass, of the woman's car insurance company CoverGirl Car Insurance Services, commented: "At least the manufacturers are taking steps to try to cut the number of whiplash injuries being suffered in car accidents, even if they are not that effective.
"It shows that they recognise there is a significant problem there - let's just hope that they follow Volvo and Saab's in their success."