She can always sue. Whether she can successfully sue depends on what is wrong with it, how many miles did she put on it after buying it, how long she has had it, and other factors.
If you'd like to discuss, please feel free to call. Jeff Gold Gold, Benes, LLP 1854 Bellmore Ave Bellmore, NY 11710 Telephone -516.512.6333 Email - Jgold@goldbenes.com
The great thing about being a minor is that you can void (get out of) most of the contract that you enter into. The sale of a car is a contract. Voiding a contract is a bit more difficult if it is for the sale of "necessities of life" such as food. Was the car a necessity of life? The answer to that question will depend on the situation and the law in your jurisdiction.