I see a lot of suggestions for HELOCs…best rate but does come with a cost of land title registration along w/ possibly an appraisal on your home.
Good idea for large purchases. All depends on how much you are borrowing and you can calculate if it's worth paying those fees up front.
Bank rates will depend on credit, dealer rates depend on what they can get from their bank rates on used cars. Just ask and negotiate. No real right answer here.