Can I Buy a Car for My Mother as My Mother’s Agent Under a Power of Attorney?

Legally, yes. As your mother’s agent under her durable power of attorney, you can, in effect, stand in her shoes and on her behalf sign any legal document she could and would sign on her own if she were able to do so. But there is always the question as to whether the other party will accept the durable power of attorney. That’s a question for whoever will be making the loan.