Basis of premium charges

Main article: auto insurance risk selection
Depending on the jurisdiction, the insurance premium can be either mandated by the government or determined by the insurance company in accordance to a framework of regulations set by the government. Often, the insurer will have more freedom to set the price on physical damage coverages than on mandatory liability coverages.

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 have an impact on the expected cost of future claims.[4] 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).[5][6]

Gender
Men average more miles driven per year than women do, and have a proportionally higher accident involvement at all ages. Insurance companies cite women's lower accident involvement in keeping the youth surcharge lower for young women drivers than for their male counterparts, but adult rates are generally unisex. Reference to the lower rate for young women as "the women's discount" has caused confusion that was evident in news reports on a recently defeated EC proposal to make it illegal to consider gender in assessing insurance premiums.[7] Ending the discount would have made no difference to most women's premiums.

Age
Teenage drivers who have no driving record will have higher car insurance premiums. However young drivers are often offered discounts if they undertake further driver training on recognised courses, such as the Pass Plus scheme in the UK. In the U.S. many insurers offer a good grade discount to students with a good academic record and resident student discounts to those who live away from home. Generally insurance premiums tend to become lower at the age of 25. Senior drivers are often eligible for retirement discounts reflecting lower average miles driven by this age group.

Distance
Some car insurance plans do not differentiate in regard to how much the car is used. However, methods of differentiation would include:

Reasonable estimation
Several car insurance plans rely on a reasonable estimation of the average annual distance expected to be driven which is provided by the insured. This discount benefits drivers who drive their cars infrequently but has no actuarial value since it is unverified.

Odometer-based systems
Cents Per Mile Now[8](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 GPS 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.


GPS-based system
In 1998, Progressive Insurance started a pilot program in Texas in which volunteers installed a GPS-based technology called Autograph in exchange for a discount. The device tracked their driving behavior and reported the results via cellular phone to the company.[9] Policyholders were reportedly more upset about having to pay for the expensive device than they were over privacy concerns.[10]

In 1996, Progressive filed for and obtained a US patent (US patent 5,797134) on their process. Progressive has also filed corresponding patent applications in Europe and Japan. UK auto insurer, Norwich Union, has obtained an exclusive license to Progressive's European patent application. They have recently completed a successful pilot test of the technology and it is now available commercially under the tradename "Pay As You Drive™"[11]

Recent theoretical economic research on the social welfare effects of Progressive's telematics technology business process patents have questioned whether the business process patents are Pareto efficient for society. Premliminary results suggest that they are not, but more work is needed. [12] [13]

OBDII-based system
In 2004, Progressive launched another pilot program to allow policyholders to earn a discount on their premiums by consenting to use its TripSense device. TripSense connects to a car's OnBoard Diagnostic(OBD-II) port, which exists in all cars built after 1996. The discount is forfeited if the device is disconnected for a significant amount of time.[14]