I with a fairly decent credit score was turned down by banks for my last car because I did not have enough credit history. I basically bit the ladies head off and ate it for dinner. Which didn't help, fyi. ;-)

I went to the dealership and they jumped for joy when they saw my credit. I've also heard them telling other people on the lot saying what you just said that if they have a co-signer with good credit they'll be able to do the loan. So, don't drop the idea due to one pissy bank. I too got declined.