Hi Mollox,
One other thing that can make the M3 feel this way is the traction control, it does cut in quite a bit and often with the slightest of flash from the yellow triangle, this often bogs the car. Try driving it with the DSC button switched off (OBVIOUSLY, TAKE A SHED LOAD OF CARE!!!) and see if you get the same.
You will find however the rear tyres let go pretty easily.
