A Vehicle Identification Number, commonly abbreviated to VIN, is a unique serial number used by the automotive industry to identify individual motor vehicles. If you were to take the VIN number to the manufacturer, they could tell you what type of engine the vehicle was originally fitted with. The actual original engine capacity can also be obtained through manufacturer records depending on the age of the vehicle.
The first three characters of a VIN number uniquely identify the manufacturer of the vehicle using the World Manufacturer Identifier or WMI code. A manufacturer who builds fewer than 500 vehicles per year uses a nine as the third digit, and the 12th, 13th and 14th position of the VIN for a second part of the identification.
Some manufacturers use the third character as a code for a vehicle category (e.g. Bus or truck), a division within a manufacturer, or both. For example, within 1G (assigned to General Motors in the United States), 1G1 represents Chevrolet passenger cars, 1G2 represent Pontiac passenger cars and 1GC are Chevrolet trucks.