I think I read that production for 2010 X5's doesn't start until Oct 1. However, my past experience with other BMW's is that your order can be moved up pretty quickly without much notice so if you are sure about changing colors or options, you should do it quickly.

In my case, my M3 moved up 7 weeks without notice. I was pleasantly surprised but there were others who were contemplating color changes who were unhappy when their production status got locked in before they could make changes.

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2012 F10 550xi Carbon black/oyster
2011 E92 M3 SSII/black
2012 W166 ML63 Steel grey/porcelain
2007 E93 monaco blue/beige (retired)
2010 E70 35d Space grey/saddle brown (retired)