There is no thing as the cheapest car insurance company. You have to compare cost from many companies. But there is 2 type of P and C insurance companies the one that can only sell their insurance such as All-State, Farmers, State Farm, ect (captive agents). And the P and c; non-captive agents compare are able to sell many different insurance companies product. In the scene they are shopping around for the best rate for you.
P and C insurance prices are based on lets call the target market. Some insurance companies want high risk people, others want very low risk people, others are some where in the middle. Some insurance companies prefer underwriting policy in a rural clients, some like urban clients. It all depends on so many factors that you have to shop around. But, the internet makes it easier to do this. You can find insurance search engines that will find insurance companies you may never of heard of before. But in fact there is hundreds of ways to search insurance compared to the old fashion pull out the yellow pages and call every company in the yellow pages.