The representative for the Alabama Department of Revenue that responded regarding how old one must be in AL to purchase a car stated that Alabama law does not provide for a minimum age requirement to own a vehicle. 

So the state of Alabama does not have restrictions on the age one must be to buy a car. Even without a state law a dealership and financing company will likely have extra requirements if you are under 18 and thus still considered a minor. Normally for registration, financing and insurance contracts or legal documents will be signed and if you are a minor then usually they will require you to have a parent or guardian sign on the forms with you.

If you are looking to buy a car as a minor then check with the dealership you wish to purchase the car from to see what guidelines they follow. For Alabama auto insurance rates, click here to get started on a quote.