If the parents took out a loan at a higher interest rate to replace a better loan, and accepted full responsibility for the loan, THEN made her sign a contract pawning it off on her after the fact, I'd say she has a chance at proving the contract unconscionable.
I'm guessing though, that the new loan is actually much better, but probably has a 3 year versus a 5 year payback or similar circumstance.
But hey, listen.. I'm a parent AND not so old that don't remember what it's like to be 21. You've tasted autonomy for a couple years now so being back under the 'rents thumb all kinds of sucks I realize. From what you've written though, your parents went out on a limb to pay for this car, and legally they are on the hook for it. They don't appear to want to profit from you in any way, and simply want you to show that you take the situation seriously. My experience tells me that your parents never had any intention of this contract seeing the light of court, it is primarily symbolic in nature, and a formal way to make sure you're on the same page. Try not to blow it out of proportion. If you feel the increased amount per month is TRULY a hardship, try and compromise with them to pay it back over the longer period and convince them that the original payment is what you knowingly signed on for. They may or may not work with you on that, but I'm guessing if you had a hard month somewhere down the line they wouldn't force a court issue on you to let a payment slide to the back end or something. Meet them halfway and make a genuine effort and this is gonna work out fine.
