What are my chances of financing a vehicle?

I am 21 years old and I'm looking to buy a used vehicle from a dealership for approx. 20-25k. I have no credit. However I have a full time job that I have been at for well over a year now, have a 3k down payment, and I have been with my bank for over 3 yrs now. Have never over drawn my account and have no problems with them financially. Would I still need a co-signer to be able to purchase the vehicle?