PRICING PLANS
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.
For mandatory liability insurance, in some countries risk factors are taken into account (giving varying prices) and in others a fixed rate is charged regardless of the individual circumstances.
Exposure bases
Flat rate
Car insurance plans routinely charge a flat per-car/per-year price regardless of how much the car is used. Since a time unit provides no actual measurement of the actual miles of driving exposure each car consumes during the insured year, insurers have no credible statistical basis for the cost comparisons used to support price classifications.
Reasonable estimation
As a sales enhancement, many car insurers offer a "low estimated future mileage" discount to customers who predict that the car's mileage will be below some stated limit during the next premium period. There is no verification involved and no additional charge if the car is subsequently driven more than the stated amount. This arbitrary discount tends to foster customer belief in the mistaken idea that "miles" are just one of many classification factors used to raise or lower prices from the territorial base rate. In fact, odometer miles (which insurers do not use) are not a factor but a metric - the only valid basis for measuring each car's consumption of insurance protection in on-the-road use.
Odometer-based systems
Cents Per Mile Now (1986) advocates classified odometer-mile rates. After the company's risk factors have been applied and the customer has accepted the per-mile rate offered, customers buy prepaid miles of insurance protection as needed, like buying gallons of gasoline. Insurance automatically ends when the odometer limit (recorded on the car's insurance ID card) is reached unless more miles are bought. Customers keep track of miles on their own odometer to know when to buy more. The company does no after-the-fact billing of the customer, and the customer doesn't have to estimate a "future annual mileage" figure for the company to obtain a discount. In the event of a traffic stop, an officer could easily verify that the insurance is current by comparing the figure on the insurance card to that on the odometer.
Critics point out the possibility of cheating the system by odometer tampering. Although the newer electronic odometers are difficult to roll back, they can still be defeated by disconnecting the odometer wires and reconnecting them later. However, as the Cents Per Mile Now website points out: "As a practical matter, resetting odometers requires equipment plus expertise that makes stealing insurance risky and uneconomical. For example, in order to steal 20,000 miles of continuous protection while paying for only the 2,000 miles from 35,000 miles to 37,000 miles on the odometer, the resetting would have to be done at least nine times to keep the odometer reading within the narrow 2,000-mile covered range. There are also powerful legal deterrents to this way of stealing insurance protection. Odometers have always served as the measuring device for resale value, rental and leasing charges, warranty limits, mechanical breakdown insurance, and cents-per-mile tax deductions or reimbursements for business or government travel. Odometer tampering—detected during claim processing—voids the insurance and, under decades-old state and federal law, is punishable by heavy fines and jail."
Under the cents-per-mile system, rewards for driving less are delivered automatically without need for administratively cumbersome and costly technology. Uniform per-mile exposure measurement for the first time provides the basis for statistically valid rate classes. Insurer premium income automatically keeps pace with increases or decreases in driving activity, cutting back on resulting insurer demand for rate increases and preventing today's windfalls to insurers when decreased driving activity lowers costs but not premiums.
Source: http://en.wikipedia.org/wiki/Car_insurance
