The ECJ in Luxembourg declares cheaper car insurance for women "discriminatory", so it must be gone by December 2012. Apparently this will see car insurance premiums for women go up by as much as 25%.
It is usually claimed that the difference in premiums is because women are safer drivers. They are not - they simply drive less.
According to the 2009 Annual Travel Survey (pdf), "overall in 2009, females made 5% more trips than males. However, males travelled 19% further than females, averaging 7,380 miles a year compared with 6,193 miles respectively." Would a 19% difference in average miles travelled per year account for the difference in insurance premiums between the genders? Why, yes, it would.
Women crash less because they drive less, not because they drive safer. Insurers have, to date, simplified their response to this phenomenon by offering women cheaper premiums than men. Now they're not allowed to use this basic profiling shortcut my initial guess is that the fairest way to achieve the same outcome will be to price insurance on the basis of miles driven, since this will reflect much the same basic insight - that the more you drive, the more you crash and the greater the risk your insurer bears.