They produce prototypes of models that travel around the globe for internal events and marketing purpose well ahead of the launch. The M3 is one such model that has to be showcased to the BMW global distribution network so they can commence preliminary marketing work for their country.
Two examples are if you will. The BMW M6 Gran Coupe. The car does not go on sale until next summer. But BMW UK are already showing a RHD example in preliminary marketing.
The second is the BMW X5 which shows that a lot of the marketing on this model and others are almost complete even though the car is still months from launch.
Given the launch of the BMW M5 Concept at Shanghai 2011 it is always a possibility that the M3 Concept could appear at the Shanghai auto show in 2013. Again for similar reasons why the M5 appeared. M sales in China are again in double figures in percent increase and every second M3 built goes to a customer in China. Chinese customers are also going crazy for the 3er in both standard and extended wheelbase options.
Then of course there will be another M festival in 2013.