By Federal Law a vehicle model year can only have "one" January 1 in its model year. In the United States, for regulation purposes, government authorities allow cars of a given model year to be sold starting on January 2 of the previous calendar year. Clear as mud? It means that you can come out with a 2011 model AFTER Jan. 1, 2010 and have a maximum manufacturing period from Jan. 2, 2010 until Dec.31, 2011. This gives the vehicle only "one" Jan 1 date in its manufacture. This is usually done by a manufacturer for a model year where there has been significant change and gives the manufacturer an extended model year to roll it out. Another way to look at it is: If the manufacturer came out with a 2011 ON Jan 1, 2010 the 2011 model would have to end by Dec. 2010 since the vehicle had its Jan 1 date already.