The insurance companies classify all cars to different insurance groups.
The car security
Let's say your car got coded audio equipment and good locking device for alloy wheels. An active alarm system with security door locks. All this features affects your premium and if you use them it will lower your insurance premium cost.
Damage and repair
Long repair times for damages is rating the insurance group of the car. Longer repair times often means higher costs. So availability of body shells is an important factor. The cost of the car parts also sets the group rating.
car value and performance
The insurance companies uses the prices of a new car as a guide line when it comes to calculate and set the group rating. The price of the new car gives a hint of what repair and replacements should cost in the future. The insurance companies also know as well that high performance cars very often result in insurance claims. After all they got there statistics. So a car with a big engine and great performance will cost you more to insure.
How about imported cars?
If you import a car from another country, you can always get a temporary insurance for one month and then search for a better car insurance offer somewhere else. The car insurances of imported cars are often pricey and not all insurance companies deal with imported cars.
Mileage affects the premium of the car insurance
Do your own calculations before of how many miles you do in a year. The mileage is an important factor when it comes to affect you car insurance premium. Even if you don't know how many miles you do in a year right now. Do the math and be prepared when the insurance advisors ask you. Remember to not declare less miles in order to get a lower insurance premium. This could cause unwanted consequences in the future. In case of an accident. The insurance company can estimate your mileage and then use it as a reason to invalidate your car insurance policy.