Allstate relies more on customers' credit ratings in determining their auto insurance premiums than four other major insurers, according to a new survey from WalletHub, a personal finance web site.

The other four insurers are State Farm, Progressive, Geico and Farmers Insurance. In the study, WalletHub compared price quotes for two hypothetical consumers who are the same, except that one has excellent credit, and the other has no credit.

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WalletHub discovered a 116 percent difference in premium prices between the two hypothetical consumers at Allstate. State Farm apparently utilizes credit scores the least, with a 45 percent gap between premiums for the two consumers.

Credit data is apparently least important in Vermont, which has an 18 percent difference between premiums for the two consumers. And credit data is most important in Washington, D.C., where there is a 126 percent gap. The difference averages 65 percent nationally.

Progressive is the most transparent insurer about its use of credit data in establishing premiums, while Liberty Mutual is the least transparent of the 10 insurers studied on this issue.

When shopping for auto insurance, make sure you go over the fine print and don't be afraid to inquire about any concerns related to the policy, Bankrate.com recommends.

"Ask a lot of questions," Jeanne Salvatore, senior vice president of public affairs for the Insurance Information Institute, told Bankrate. "Make sure you understand what it is you're purchasing and how much."

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