If you bought the car new and the dealer didn't disclose the repair you have legal grounds for a lawsuit. A client of mine bought a minivan new and later discovered that it had been repaired. After contacting a lawyer the dealership did cut him a nice check. Not sure what your options are but if you bought the car under the assumption it was new then my advice is contact a lawyer, but if the car was used I don't think you have any recourse.