According to Nissan, they almost sold out of all the 2012 model year Nissan Leafs in the US due to a jump in demand in the later part of the year. (source)
The automaker only had 900 Leafs on hand at the beginning of this year and will have sold most of those in January. Sales lagged behind 2011 at the start of 2012, but towards the end of the year, demand picked up substantially.
Last month, Nissan started work on the 2013 Nissan Leaf at the new Smyrna, TN plant in Tennessee. The first US-produced Leafs are set to roll off the assembly line next month.
Earlier this month, Nissan announced it was dropping the price of its 2013 Leaf by $6,400 to a new base price of $28,800.