Vin Number stands for Vehicle Identification Number and it must be on every vehicle sold inside the United States and across the world. In Europe they are known as the chassis number. The VIN is used by the government to track all motor vehicles in the united states, and is located on every vehicle title. Using the VIN number it is possible to track a vehicle's history in terms of transactions, and if it was involved in a major accident. It is also possible to use the VIN to determine a vehicle's exact make-up as delivered by the factory, and as such is used to determine the provenance of a classic car. Today, the VIN number is located on the driver's side of the dashboard, and visible through the windshield. In older cars the VIN may be located anywhere, including inside the driver's door and on the firewall.

The reason a vehicle's original equipment can be determined by a VIN is the number is assigned by the manufacturer, and is used by the manufacturer to track its own products. If you have the correct codes, it is possible to determine the date of manufacture, body style, engine, transmission and even paint color. For example with the classic 64 1/2 through 1966 Mustang the engine code C denoted the 289 engine, 2 barrel carburetor with 200 horsepower output. The A code gave the same 289 a four barrel good for 225 hp, and K code denoted the high output 271 horsepower engine used in the Shelby GT-350 though it could be ordered in a standard mustang. No matter what the owner says, it isn't a real K-code without the K in the VIN.

This matters because classic cars have become increasingly rare over the years, and the most prized have become extremely expensive. For example, Chrysler products equipped from the factory with the rare 426 Hemi option have sold for as much as a million dollars at auction. Of course such a car has to be exquisite, and the term 'numbers matching' means the car is exactly as the factory delivered it. This has led to a bit of action whereby older, severely damaged cars may have value solely for their VIN. For example a Plymouth Road Runner with a hemi VIN that has no engine, suspension and is rusted through in multiple locations may still command four figures because it has that rare VIN. Junk cars have been completely rebuilt around their VIN even though it might be much cheaper to simply put the hemi into a nicer body.

There are many websites where older VIN numbers can be checked for production dates and equipment, sometimes the manufacturer will provide the information for you upon request. Carfax and other research services require the VIN to track the car, and your insurance company also requires the VIN to identify your vehicle as yours. As the number is stamped into metal and difficult (but not impossible) to remove, it can be used to identify formerly stolen cars.

Many thanks to Albert Herring for letting me know about the numbers as used abroad. Tortoise pointed out that until the 1980s Italian car makers considered themselves above such dispassionate matters as accurate records, so the VIN numbers are the moral equivalent of pulling numbers out of a hat. They preferred to spend their time worrying about the camshafts, a sentiment I understand.