You could sue the seller for fraud.  Fraud is the misrepresentation of a material fact made with knowledge of its falsity and with the intent to induce your reliance upon which you justifiably relied to your detriment.  Fraud also applies to nondisclosure by the seller of facts the buyer could not have reasonably discovered.Your damages (the amount you are seeking to recover in your lawsuit) would be either the benefit of the bargain or your out-of-pocket loss.  Benefit of the bargain means the defrauded purchaser can recover the difference between the real and represented value of the property (car in this case) regardless of the fact that the actual loss may have been less.Out-of-pocket loss is the recovery of the difference between the price paid and the actual value of the property (car) acquired.A lawsuit can be filed where the plaintiff resides or where the defendant resides or where the claim arose.  You could file your lawsuit in MA or NH.  For your convenience in filing documents with the court and appearing in court, it would be preferable for you to file your lawsuit in MA.  You can have the lawsuit served on the person who sold you the vehicle by a process server located in or near the city in NH where the seller resides.  Process servers are listed under attorney services in the Yellow Pages or on-line.You do have a good case for fraud, but it is not possible to predict the outcome in court.