[BMWM5NYC]

It is the fan that turns on sooner and stays on longer in sport plus mode. Same thing on the M5. You can really notice it in the winter time. If you start your car and put it into sport plus, you can hear the fan come on much earlier and it takes a lot longer for the car to warm up above the T'stat opening temperature. Also the M5 has a VARIABLE GEOMETRY PUMP which increases and decreases flow through out the cooling circuit by use of movable vanes. So in Sport plus the vanes are wide open, compared to partially opened in sport and eco modes. I would think the M3/M4 would be the same.