In American English, a lemon is a vehicle that turns out to have several manufacturing issues affecting its safety, value or utility.
These errors can range from parts being installed incorrectly to a tool that was used to build the car not being removed or a batch of materials with structural or chemical flaws.
The idiom "Friday afternoon car" was used to describe new cars that had been delivered with numerous faults or suffered from an excessive number of warranty claims early in their lives – based on the premise that assembly line workers were far more likely to make errors at the times when they were perceived to be least interested in the standard of their workmanship.
Consumer protection legislation typically labels vehicles as "lemons" if the same problem recurs despite multiple repair attempts (such as three times in a row over a short period, where previous attempts have not corrected the problem) or where defects have caused a new vehicle to be out of service for a prolonged period (typically 30 days or longer) for repairs.
The purpose of the Act was to make product warranties more easily understood and enforceable, and to provide the Federal Trade Commission with a means of better protecting consumers.