when the lever is in sport mode the 4 you see indicates the maximum gear the car will go into. it isn't a true semi-auto, all you can do is lock out higher gears. It just defaults to 4 for some reason.
(eg set it to 2 and it will use 1st and 2nd. set it to 4 and it will use 1, 2, 3 and 4. etc etc)
Go through the trip computer and you'll see another set of numbers indicating the actual gear the car is in.
Oh yeah, and max torque is somewhere above 4000rpm