I reckon its not a typo. I think BMW did this purposefully and leaked it to see peoples responses. Its the same thing with the M5 being turbo. People complaint endlessly on the large forums. When test results started coming out with the X5M, X6M and 550i people have become more relaxed. Talk is the new M3 is a V6 twin turbo. Someone has told me this two years ago and I just laughed. Slowly its being leaked that potentially it is the motor its going to get. The engine does exist though but you never know what the marketing dudes decide because end of the day its up to them.