My dad thinks I'm too immature to take drivers ed or get my learners permit?

From the way you explained it, it seems as if you already proven yourself to be mature. The thing is Your dad and mom know youre mature. Your dad's reason for not permitting you to take drivers ed is not his real reason. You have to understand that he wants for you to be safe and sound. It doesnt have to do anything with being mature. Think about it. Hes really just concerned for your safety. Try talking to him about this. Ask him "Are you not letting me do this because youre worried about me?" If he admits then you persuade.