I know the only real way to determine MPG is by calculating it yourself, but if it helps in the month I have had the M the reported fuel consumption has been 25.6* vs about 30 - 31 in my 3.0si. So if that's to be believed it's only 5 MPG worse off...
[*] yes I know that probably means I'm not driving it hard enough!
[*] yes I know that probably means I'm not driving it hard enough!