A 17-year old is consider a minor, and minors cannot obtain loans on their own, according to CarsDirect. Many banks don't allow a minor to obtain a loan even with a co-signer. This is because a loan is a legally binding contract, and minors cannot enter into contracts.
Minors do not have any credit built up, so when they become legal adults, they still may have trouble obtaining loans without a co-signer. In order to help a minor child build up some type of credit, there are many banks and financial institutions that have accounts designed specifically for teenagers, reports DoughRoller. These accounts help teach children how to manage money efficiently.