Women drivers aged 17 to 25 could see a £4,300 increase in their insurance costs if EU judges make it illegal to assess premiums on the basis of a policyholder's gender, according to Open Europe, the think tank campaigning for EU reforms.
In a "worst case scenario", the figure could hit £9,300, the organisation warned.
The Association of British Insurers said the EU ruling, due on Tuesday, could cost female drivers about 25% extra in premiums, while male motorists could save some 10% in car insurance rates.
This would mean that male drivers may save up to £3,250 in insurance premiums, Open Europe said.
The think tank also estimates that insurance firms will have to raise £936 million more capital to cover themselves against "new uncertainties" caused by the ruling.
Stephen Booth, Open Europe research director, said: "Giving EU judges free reign to rewrite laws that the UK Government has signed up to in good faith can cause hugely damaging and unforeseen consequences. That these judges would magically rule that young women should pay more in the name of equality is simply perverse. Instead of making prices fairer between men and women, this ruling would increase costs for consumers taken as a whole."
© Press Association 2011