Except for government-mandated liability insurance, most car insurance plans charge a premium based on several risk factors that are likely to have an impact on the frequency of occurrence or on the expected cost of future claims. The premium usually depends on the car characteristics, the coverage selected (deductible, limit, covered perils), the usage of the car (commute to work or not, predicted annual distance driven), driving history, as well as the age and, for youth rates, sex of the driver. Adult rates are generally unisex.
Source:
http://en.wikipedia.org/wiki/Car_insurance
