All the information you supply is encrypted and secured by the company you apply to. It won’t be shared with other insurance providers unless you request that it be. Likewise, if credit history information is used in the generation of your car insurance quote, your credit score won’t be affected.
Depending on the service, you are either given an instant free auto insurance quote, or you are contacted via email with several offers. In either case, your information is private and secure. Once you get a quote, you can choose to purchase the policy online or via ground mail. The company you’ve chosen will provide the details.
If your information is correct, you should get the rate you’ve been quoted. However, errors in your application or additional information gathered by the insurance company (like your credit score) may prompt them to change the quote.