Focus ST heavy on fuel, I used one for a week and couldn't get more than 17MPG average. Too tempting. Sounds great with the turbo'd five-pot. Good points above CK, but I firmly believe that buying a car such as the ST or Type R is emotional, not rational. So, Subaru Sam, get your ass in the drivers seat and see which you prefer driving.
Instead of the BMW Diesel, you would be better served with a Focus TDCI and have more money left.
JJ