In order to get a loan, an individual must be at least 18. According to CarsDirect, teens under age 18 remain minors, and legal contracts they sign are not binding.
Once a teen turns 18, many lenders remain leery about providing them a loan. Since the teens have been unable to borrow money up until this point, they have no credit history and often have limited income. About.com indicates that many lending institutions require young borrowers to have a cosigner. However, serving as a cosigner for an 18 year old is risky. Late payments affect the cosigner's credit rating, and if the teen does not pay the loan, the cosigner is responsible.