In the UK, you insure the car. In the US, you insure the driver (within a range of cars).
Insurance companies employ statisticians to work out the risk of insuring cars, which is based on all sorts of things. Primarily it is the claims associated with the car, and the claims associated with the age group and where you live. Things like repair costs are also included. (By the way, the stats job is not underpaid if you're inclned to maths and looking for a career!!)
However, the overall way an insurance company is run is that they take in premiums and pay out claims. Providing premium income exceeds claim payments, they make a profit. If they make a better profit, they can afford lower premiums. If they pick and choose who they insure, they can also afford lower premiums. So, researching the lowest risk cars and areas to live, and who's made the most money, often helps lower premiums.
For what it's worth, I've been with Direct Line for over 15 years, and they've never been beaten at renewal time. HTH
