Is the Vehicle Identification Number unique?
Since the 1980’s, most VINs are unique combinations of 17 alphanumeric characters identifying each specific vehicle as defined by ISO 3779 and ISO 3780. Within the 17-digit number are codes that indicate the vehicle's make and model, manufacturing location, manufacturer value (the ''world manufacture id'' - WMI, controlled by SAE registration), optional equipment, and a manufacturing sequence number, etc. A vehicle identification number is normally assigned by the original equipment manufacturer (OEM), but can be assigned by titling or registration agencies or by secondary manufacturers or finishers.
It is important to note, that VINs are not unique at times. In early uses, many of the ''fly by night'' finishing firms would assign the same VIN for similar products. There are also rule exceptions for older or more exotic vehicles with less than 500 vehicles that result in duplicate VINs. Most law enforcement CAD systems, if they recognize exceptions will prompt the user when the make/model values encoded in the VIN do not match the information