I don't have a down payment. Can I use my vehicle as a down payment?
This is kinda a situational question, Yes, you can trade a vehicle with no down payment. The problem comes when you owe too much on your trade, and you're carring alot of negative equaity over on to the vehicle you're purchasing. As long as your credit is good they're are banks that will loan 140% of nada trade value.
If the dealership can fit your negative equaity into that 140% then you want need a down payment, but if it goes over then you'll have to cover the difference. But this is broad answer because other factors play apart in whether you need a down payment. Credit, payment to income, debt to income are other factors that play an important role.