Although the rules vary from state to state, dealers must inform customers if a car has a rebuilt title. Actually, there is little they can do about it as the title will usually say it is a “salvage” car or that the title was “rebuilt.” Given the state of consumer law in the US, it is virtually mandatory for a buyer to be informed of this information so that the buyer can make an informed decision. If the information is withheld, then the dealer may be liable for fines and penalties under state laws, although the amount varies from jurisdiction to jurisdiction. It also makes marketing sense to divulge this information.
For more info, see Things to Know About a Rebuilt Car Title