Figures released by the Government last year revealed that only 30 per cent of teenagers in care attain at least one GCSE or GNVQ, leading to the assumption that most of these youngsters are of limited academic ability.
But the study - the first of its kind - used a "best value" model to examine the academic performance over five years of Coventry's 350 looked-after children and found no relation between their key stage 3 and 4 results.
Young people in care who had achieved good results at the end of Year 9 were just as likely to leave school with no qualifications as those who had consistently failed.
In total, an average of only 4 per cent of Coventry's youngsters in care left school with five or more A*-C GCSEs between 1995 and 2000, compared to 38 per cent of all the authority's pupils.
The looked-after children were almost seven times more likely to be excluded than other pupils, more than six times more likely to truant and more than three imes more likely to have a special need.
The study also found no correlation between a child's exam results and the number of times they had moved home.
This questions the Government's new target of reducing, to no more than 16 per cent, the number of children in care who have three or more placements in any one year.
Dr Ray Evans, author of the study and head of Education Access Services at Coventry council, said: "There has been a common assumption that looked-after children do not do well at school because they are not very bright. This research casts doubt on such a belief.
"It also demonstrates that we should be sceptical about blindly pursuing care targets set by central Government and striving for things that can be measured rather than things that will make a real difference.
"What is more important is ensuring that education is a top priority with those who look after children in care, providing opportunities for youngsters to socialise with children who are not in care and helping them develop a sense of responsibility."