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. 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).
In South Australia, since July 2016, CTP is no longer provided by the Motor Accident Commission.The government has now licensed four private insurers - AAMI, Allianz, QBE and SGIC, to offer CTP insurance SA. The scheme allocates one provider for 3 years as part of vehicle registration. After July 2019, vehicle owners can choose a different CTP insurer and new insurers may also enter the market. 
A compulsory car insurance scheme was first introduced in the United Kingdom with the Road Traffic Act 1930. This ensured that all vehicle owners and drivers had to be insured for their liability for injury or death to third parties whilst their vehicle was being used on a public road. Germany enacted similar legislation in 1939 called the "Act on the Implementation of Compulsory Insurance for Motor Vehicle Owners."
Type of car: If you have an expensive or powerful car then you are seen as a higher risk for a number of reasons. If it’s expensive, it has a higher risk of being stolen. If it’s powerful, it’s deemed more at risk of getting into an accident driving at speed. If you want to see how your car impacts your insurance, you can check which insurance group it’s in for an indication.
According to the Insurance Information Institute, in the United States in the early 21st century, about two-thirds of the money spent on premiums for private passenger auto insurance went to claims. More than half of this amount covered car damage. The rest covered personal injuries. The remaining third of the money spent on premiums covered insurance companies’ expenses—such as commissions, dividends to policyholders, and company operations—and contributed to their profits.
Getting comparison insurance quotes is far different today than it used to be. Historically, it cost someone money to get a look at rates from a company. In their view, they were working to get you these auto insurance quote comparisons so they should be paid for this time, whether you go with a different company or not. Typically, a company would waive the quoting fee if you bought their plan.
There are three states that do not have a private CTP scheme. In Victoria, the Transport Accident Commission provides CTP through a levy in the vehicle registration fee, known as the TAC charge. A similar scheme exists in Tasmania through the Motor Accidents Insurance Board. A similar scheme applies in Western Australia, through the Insurance Commission of Western Australia (ICWA).
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.