Back in 07 when this was new, others reported similar mpg from theirs. Remember, mine is a Co which may make a diff.
As to speedo / odo, the info I have is that the TUV is so strict that BMW calibrate their speedos to read no less than the actual speed no matter what tire used meaning they calibrate about 10% high for stock tires. The odos are supposed to be spot on. I checked and confirmed this with the GS but not with the X.
Anyway, my readings of mpg are from the uncorrected odo.
Why be born again when you can just grow up?