Model Year

The model year of a product is a number used worldwide, but with a high level of prominence in North America, to describe approximately when a product was produced, and it usually indicates the coinciding base specification (design revision number) of that product.

The model year and the actual calendar year of production do not always coincide. For example, a 2009 model year automobile is available during most of the 2009 calendar year, but is usually also available from the third quarter of 2008 because production of the 2009 model began in July and August 2008. When a brand new model is introduced there may be an additional delay to retool and retrain for production of the new model.

The variables of build date and design revision number are semi-independent. There is no natural law that forces one to be strictly correlated to the other, other than the two facts that (1) future design revisions cannot have been built in the past, and (2) most products, in most contexts, tend to be built to the design revision that was the latest one at the time of building. The idea of strongly correlating build year to design revision number took many years to become a meme in consumer culture.