Here's an interesting tidbit...
A 2002 X5 4.6is took one foot LESS to stop from 70mph than a 2013 BMW M5.
Pretty impressive considering the M5 weighs almost a thousand pounds less AND has 6 pot brakes in the front.
BMW X5 4.6is - Short Take Road Test - Car Reviews - Car and Driver
2013 BMW M5 Road Test – Review – Car and Driver