Most insurance companies allow a newly licensed 16-year-old the ability to purchase an insurance policy. However, you will need a parent or a legal guardian to sign the application with you. Since you a minor, your policy will be 'void' if your parent or legal guardian does not sign the application with you in most cases since as a minor the insurer requires an adult to sign on with you to make the legal contract valid. This is a good thing for your parent or legal guardian. Because your parent or legal guardian is responsible for you and your actions in the eyes of the law, they can make sure you are purchasing insurance that will protect his or her financial interests.
If you are looking to buy a car at age 16 you should contact your state's Department of Motor Vehicles (DMV) to first find out if there is a minimum age at which to buy, register and title a car in your name. In some states they do have a minimum age of 17 or 18 while in others you can buy and title a car in your name at any age.