The term number matching or numbers matching refers to an automobile that is built entirely of the same parts that it came off the assembly line with. When manufacturing a vehicle, a build sheet is used to ensure that all of the proper parts are placed on the vehicle. Each of these parts is assigned a code or number matching the build sheet. Larger components such as engine blocks, cylinder heads and transmissions have the build date cast into their cores. In order to authenticate a purely stock and correct vehicle, the number matching begins comparing the actual parts with the build date, code and option list of the original build sheet.
In terms of resale, a number matching vehicle can be worth several times what a non-matching vehicle might sell for, should a serious collector be interested in the vehicle. For a vehicle that is going to be driven daily and will be purchased by someone who simply wants a nice car to drive, number matching is typically not that important. This is the difference between a car that is a daily driver and a show-quality collector vehicle. This does not, however, require every part of the vehicle to be original.
The difference between an original vehicle and a number matching vehicle can be difficult to identify for the novice as well as to the serious collector. Most vehicles come from the factory with the entire or partial vehicle identification number (VIN) stamped somewhere on it. When purchasing a number matching original vehicle, the buyer must be prepared to spend the utmost amount of money for the vehicle. This type of vehicle is extremely rare in muscle car circles due to the racing and customization that these vehicles typically encountered straight off the showroom floor. In some U.S. models, it is difficult to identify the parts that were fitted by the factories since there were many behind-the-scenes vehicles built and sold by the manufacturers to be used in racing applications.
With vehicles such as the Chevrolet Corvette, there are collector clubs that now own the original build sheets for every Corvette ever produced. This list allows the club to verify and certify a number matching vehicle and place it in its registry, attesting to the authenticity of the vehicle. These number matching certifications are so important that owners travel with or ship their vehicles across the country and even around the world in order to have them verified.