The advice I would give is not to purchase a new car honestly... unless you are only getting the loan in hopes of boosting your credit score. You would but a cargo ship in interest over the life, I am frankly suprised that the interest rate is only 12%. IF you can pay the loan off in 6 months get whatever car you want but if not I would get the cheapest car you drive safely and work on getting your score up.
You can try to go through a credit union for financing now. Or try capital one's prequalifier.
Or you can take the deal and refinance in 6 months with a credit union like DCU, Penfed, Navy Fed.
Don't be so hard on yourself, most of us have also had credit scores in the 400's at some point. Read here and you can change your scores over time.
Is there a particular reason your score is so low? You may not be able to refinance if they are other underlying factors keeping your score low so keep that in mind as others chime in.