There is a variety of federal law that applies in cases of motor vehicle sales fraud.
One requires the placement of a window sticker that accurately depicts the car's status as new or used. 16 Code Federal Regulations (CFR) 455. There is the odometer disclosure rule: 49 CFR 580.1. Your state will have its own version of its "lemon law".
Remember that your facts must be accurate and this requires documentation. Be sure to consult with your local attorney. Do not attempt to file an action in state or federal court without competent legal counsel.
You MAY have a lemon law claim under Texas law, but the criteria are VERY narrow. If you win at the administrative level, you get a replacement vehicle and continue paying on the note if any OR you surrender the vehicle and get a cash settlement paid to the lender and you remain liable for any remaing balance on the note. If you lose, you can appeal to a district court, but the suit MUST be brought in Austin.
You also have a claim against your car dealer for deceptive trade practices for selling the car as new when it was not. That claim would have to be coordinated with the lemon law claim.
If your sales contract says the car is new when you buy it, but it really isn't, then in most states that would be a breach of the contract, an unfair or deceptive act in violation of most state Udap laws, and probably a violation of one or more other consumer protection laws, either federal or state. 2 things to remember. First, for every legal right you may, there is only a limited amount of time within which to file a lawsuit or you lose your legal rights and you are stuck. Second, sueing a car dealer is not easy and you should talk to a local Consumer Law attorney near you. Call your local attorney Bar Association and ask for a referral to a local Consumer Law attorney, or, you can check this 50-state Consumer Law Attorney List, where attorneys who regularly handle Lemon Law and Consumer Law cases are listed at no cost to them: http://ohiolemonlaw.com/locate-a-local-attorney.shtml