You can't compare auto to manu transmission. Moreover, the age of the car would also affect 1st& 2nd gear pick-up speed. Beemer's VANOs is also known to degrade with mileage. (Something to do with the seals). Some people even testified better pick-up speed after a change of the transmission oil &filter (which is supposed to be lifelong).
To suggest our Z4 is slow on the pick-up will offend us owners here. Did you press the SPORTs button or not?
0-100 i reckon is around 7 seconds.