The easiest way is to enter the VIN number for the car into Carfax.com's database. You can also take the car to a reputable mechanic and pay for an examination.
It's a good idea to check this out before buying. You should also ask the seller this question. If you find out later that he/she lied to you, it could form the basis for a fraud claim against them and entitle you to a refund. It's best to get that information in writing from the seller so there's no confusion if the matter comes up in the future.
Carfax and Auto Check are common resources and there's a new federally-backed database too, but they all cost money. Wrecked and repaired cars can be dangerous because you don't know the quality of the repair job or the repairman. Many car dealers will run a CarFax before they sell cars off their lot, although they are not required. CarFax has done a good job of advertising itself, but it isn't always accurate. They get their information from insurance companies and car dealers and title departments and lots of other places so it seems to be about 80% accurate, more or less. However, the existence of an accident on the CarFax report seems to almost always be accurate in our experience. If the dealer ran a CarFax (and the CarFax company keeps track of who runs their reports), then it was on notice of the accident record and all else on the report. If your report shows an accident before the dealer bought the car, then the dealer's report probably did too. Car dealers generally have a higher disclosure obligation than an ordinary consumer would have selling the car. If the dealer knows something and realizes that the buyer would want to know about it, but doesn't disclose it, the dealer may be committing fraud by concealment. Every state has its own definition of fraud, but generally it's a lie or something kept hidden that costs you money. There is a big difference in value between a car that has never been wrecked and one that has, even when the repairs are done right. It's called "diminished value" and it means your car is worth much less than one that was not wrecked and repaired. You probably have the right to either cancel the deal or recover the amount you were overcharged for the car. If you want to know what your car is really worth, take it to a car dealer and see how much they will give you for it after you tell them that the CarFax for it says it was wrecked and it may have frame damage. Many car dealers won't want to buy it at all. If you got a wrecked-and-repaied car without knowing it, then you should talk to a local Consumer Law lawyer about your state laws and what your rights are, right away. Call your local attorney's Bar Association and ask for a referral to a Consumer Law attorney near you or you can go to this web site page for a Free Online 50 State National List of Consumer Law Lawyers (http://www.ohiolemonlaw.com/ocll-site/ocll-locate_local.shtml) and find one near you (lawyers don’t pay to get listed here and most of them are members of the only national association for Consumer Law lawyers, NACA.net). But act quickly because for every legal right you have, there is only a limited amount of time to actually file a lawsuit in court or your rights expire (it's called the statute of limitations), so don't waste your time getting to a Consumer Law attorney and finding out what your rights are. If this answer was helpful, please check the box below.