Two of the most important factors that go into determining the underwriting risk on motorized vehicles are: performance capability and retail cost. The most commonly available providers of auto insurance have underwriting restrictions against vehicles that are either designed to be capable of higher speeds and performance levels, or vehicles that retail above a certain dollar amount. Vehicles that are commonly considered luxury automobiles usually carry more expensive physical damage premiums because they are more expensive to replace. Vehicles that can be classified as high performance autos will carry higher premiums generally because there is greater opportunity for risky driving behavior. Motorcycle insurance may carry lower property-damage premiums because the risk of damage to other vehicles is minimal, yet have higher liability or personal-injury premiums, because motorcycle riders face different physical risks while on the road. Risk classification on automobiles also takes into account the statistical analysis of reported theft, accidents, and mechanical malfunction on every given year, make, and model of auto.

Cents Per Mile Now[48] (1986) advocates classified odometer-mile rates, a type of usage-based insurance. After the company's risk factors have been applied, and the customer has accepted the per-mile rate offered, then customers buy prepaid miles of insurance protection as needed, like buying gallons of gasoline (litres of petrol). Insurance automatically ends when the odometer limit (recorded on the car's insurance ID card) is reached, unless more distance is 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.

As a practical matter, resetting odometers requires equipment plus expertise that makes stealing insurance risky and uneconomical. For example, to steal 20,000 miles [32,200 km] of continuous protection while paying for only the 2000 in the 35000 to 37000 range 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 [3,200 km] 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.
You’ll notice that none of that liability coverage pays for your car or injuries, nor for any injuries your passengers sustain if you cause a wreck. This is why many people — particularly those whose car isn’t yet paid off — want “full coverage” car insurance. This isn’t actually a type of coverage, but instead typically refers to policies that include liability coverage, plus comprehensive and collision coverages.
Auto insurance is financial protection, and not just for the investment you made when you bought your car. After a really serious accident, bills for damage and injuries can easily reach into hundreds of thousands of dollars. If you happen to cause such a wreck, the victims could sue you. In the worst case scenario, assets such as your savings and home could be seized.