So I just read a great article on E85
(click here)
So I think this E47 is using the O2sensor reprogrammed which can adjust in a small window resulting in what Zm2 was referring too... So basically if your 50/50 Ball park your good for that window how ever big that window is...
Scroll down about 1/4 way to "Why stock engine management systems can't adapt to E85:" if you don't like reading it all...