We ended up invovled with the state A.G.'s office investigating our dealer. They 'accidentally' put a typo in my wife's SSN when pulling the credit report. That justified a higher interest rate - which they offered us without explaining why.
We weren't super worried because we were going to pay the car off in a couple months anyways, we just wanted the financing to shift some cap gains taxes to a different year. Then we got a letter in the mail from the lender explaining why our interest rate was so high.
We called the dealer - and almost no questions asked they offered to send us a check for the difference. Red flag raised we filed a complaint with the state A.G., and it turns out it was a common practice at that dealership.