No two drivers are the same, which is why car insurance premiums are typically calculated based on a number of diverse factors, including your age, location and the type of car you're currently driving. In short, your insurer will offer you cover based on the likelihood of your car being stolen or involved in an accident, based on historical statistics.
More expensive cars are more likely to attract a higher premium, due to the fact that they're more costly to repair and replace in the event of theft or an unexpected accident. That said, there are also certain cars that tend to be targeted more by thieves, and thus represent a greater risk for the insurer, especially if they're easy to steal. Remember that these premiums can increase over time, in line with repair costs, which are influenced by inflation irrespective of the vehicle's age.
Another factor to take into consideration is the regular driver of the vehicle. The person who drives the vehicle most often will be evaluated based on their age, previous insurance track record and the amount of time spent on the road to date. Drivers under the age of 30 are likely to pay higher premiums, as they are statistically more likely to be involved in an accident due to limited experience.
Security is another big factor when it comes to calculating your risk. Your insurer will want to know where your car is typically parked, and you're likely to have to shell out a bit more for street parking than a private garage, which is considered more secure. However, you are likely to be able to shave a little off that monthly premium if you have an approved tracker and alarm system in place, as these deterrents slightly offset the risk of theft.