First, Tesla’s Model S sedan downloads firmware updates on a regular basis. These software changes go much further than simply changing user interface elements on the dashboard. Instead, they may modify major elements of the car from its suspension to its acceleration and handling characteristics.
Secondly, in a break from traditional automobile practices, rather than waiting a year to roll out annual improvements to its Model S, Tesla has been continuously improving its product each quarter on the assembly line. There are no model years to differentiate a Tesla Model S built in 2012 from one built this year. (The last time this happened in auto manufacturing was the Ford Model T.)