Consumer Reports says that car insurance pricing doesn't work the way it used to. A couple of big differences.
Your credit score is a bigger determinant of insurance price than your driving record. A person with a high credit score and a DUI conviction can get a lower insurance rate than a driver with a perfect record and a low credit score.
Your sensitivity to price also determines your rate. They get this information presumably from credit card companies, supermarkets, department stores, perhaps Amazon. If you tend to buy more expensive things and don't do a lot of price comparisons (something Amazon would know, for example) they give you a higher price. That's why if you call them and ask for a lower price, often you'll get it. This practice is illegal in a few states, it should be illegal everywhere.
I found #2 shocking, and wanted to share it because I personally didn't care if companies knew what brand of bottled water or canned soup I buy, but now I can see why it costs me money that they do know. If you're a carefree shopper, it costs you more ways than you might think.