I recently replaced the fuel filter on my son's 2008 Mini Cooper S. It has the BMW-style fuel pump and filter in the fuel tank under the rear seat. The good thing is that everything is visible after the top cover is removed (unlike an early Boxster fuel filter).
This is a good reminder why you should replace the fuel filter every couple of years (and don't believe that a fuel filter is good for the life of the car!). I never knew/realized that gasoline was so dirty!
New (left) vs old filter (right)...
I siphoned out the fuel that surrounded the filter (inside the fuel filter/pump assy but on the tank side of the filter) and this is what it looked like. Pretty disgusting...