That would be #6. I've attached a PDF doc that I saved the hidden functions menu to (thanks JOFJ) so you could have it handy in the future.
Be sure to share your findings. I'm curious to know how this will all resolve out. I'm also curious to find out if there is a difference in MPG between your M56 vs my M54.
EDIT: Upon further research, you may be achieving optimum MPG for your bimmer. According to fueleconomy.gov, your bimmer is rated (under the revised 2008 EPA estimate) for 17-MPG city and 25-MPG Highway. That being said, my personal experience is that you can achieve 5 - 10% better than the revised estimates.
Last edited by HacksawMark; 03-04-2013 at 03:55 AM.