We have finally been able to obtain a final US 1M production figure for all those curious. The final count for US 1Ms was 740 units, per BMWNA M Manager, Matt Russell
The very first one imported was the Valencia Orange 1M Pace Car which debuted at the Rolex 24 hour race at Daytona.
We received some insight at the Detroit NAIAS as to the reason the 1M production run wasn’t extended into the 2012 model year. It was not due to any issues related to engine/emissions certification, but simply because BMW could not get enough MY2012 production to justify homologation. This had the added benefit of preserving the exclusivity and value of the 2011 1M models.