When the premium is not mandated by the government, it is usually derived from the calculations of an actuary, based on statistical data. The premium can vary depending on many factors that are believed to affect the expected cost of future claims.[38] Those factors can include the car characteristics, the coverage selected (deductible, limit, covered perils), the profile of the driver (age, gender, driving history) and the usage of the car (commute to work or not, predicted annual distance driven).[39]
On 1 March 2011, the European Court of Justice decided insurance companies who used gender as a risk factor when calculating insurance premiums were breaching EU equality laws.[42] The Court ruled that car-insurance companies were discriminating against men.[42] However, in some places, such as the UK, companies have used the standard practice of discrimination based on profession to still use gender as a factor, albeit indirectly. Professions which are more typically practised by men are deemed as being more risky even if they had not been prior to the Court's ruling while the converse is applied to professions predominant among women.[43] Another effect of the ruling has been that, while the premiums for men have been lowered, they have been raised for women. This equalisation effect has also been seen in other types of insurance for individuals, such as life insurance.[44]
Widespread use of the motor car began after the First World War in urban areas. Cars were relatively fast and dangerous by that stage, yet there was still no compulsory form of car insurance anywhere in the world. This meant that injured victims would seldom get any compensation in an accident, and drivers often faced considerable costs for damage to their car and property.