If this was the case, they'd have asked for the car back. It's possible that they got the loan bought with only one buyer. If so, you have no legal right whatsoever to return the car, and there are no laws to compel a dealer to take it back. Contrary to popular belief, there is NO federal 1/3/7/14/30 "right to rescind" law. The law that people reference specifically excludes vehicles. California offers you the option to buy the option return a vehicle within three days, otherwise, there are NO states with these laws on the books.
You cannot possibly claim that you were not informed of the terms of the loan. You signed a Bill of Sale, a contract, and a Truth in Lending form, among others, all of which have the terms of the deal on them. You were informed, you just didn't pay attention.
20 years retail auto sales experience.