It will depend upon state laws at what age a person can legally have ownership of a vehicle. State laws can differ from one state to the next regarding the minimum age they will permit a person to own a motor vehicle. So your state may or may not allow you to title and register a car solely in your name at the age of seventeen (17).
In general though a juvenile cannot enter into a contract so thus cannot be a sole owner of a motor vehicle. A minor cannot normally actually own property. His or her parents technically own that property. If a parent will co-sign on a loan for a car, the juvenile can buy a car, but the parent will be the legal owner.
There can be exceptions to this generalization depending again upon state laws. So you will need to contact the Department of Motor Vehicles (DMV) for your state to find out at 17 if you title and register a car in your name only or if you will need a parent or guardian to sign on it with you. For some examples of state laws see the see below.
In North Carolina the DOT states that their laws do not set a minimum age limit as to ownership of a vehicle as long as the owner can sign their name on the application of title. However a plate cannot be issued without proof of owner having liability insurance on the vehicle.
As the NCDOT notes, insurance companies normally will require you to have a parent or guardian sign your insurance documents (contract) if you are under 18 years of age and thus still considered a minor in the eyes of the law. Be prepared for the parents' insurance rates to skyrocket; insurance rates for teenagers are always high, and they slowly drop until the driver is 25.
In Texas the TX Department of Transportation states there are no age restrictions in order for an individual to be recorded as the owner of a vehicle. However they also go on to say that insurance companies may impose age restrictions on persons they insure and may charge higher premiums for certain age groups. Since proof of financial responsibility (liability insurance) is a prerequisite to obtaining Texas registration, an individual's ability to obtain this insurance may limit his ability to register his vehicle.
Even those states that will permit a teenager to register a car may require a parent or guardian to sign on any legal documents or contracts since they are still a minor. The Ohio Bureau of Motor Vehicles (BMV) states if you are under 18 and want to title a vehicle, your parent or legal guardian must complete a minor consent form. A parent or legal guardian must also accompany you when you appear in front of the Clerk of Courts title office staff to have a vehicle titled in your name in Ohio if you are a minor.
Once you find out your state's laws for titling and registering a vehicle you then can contact insurance companies for quotes and for their guidelines on a minor obtaining a policy. Most insurance companies will require a parent or guardian to sign on an auto insurance policy with you since it is a legal document.