The Z4 has the Sport button as well. I really dislike the whole concept of the Sport button because I think you should have all of the car's potential on-hand all the time, rather than pushing a button. From what I've read/heard, it really changes the way the M3 drives. I know personally I am always driving in a sporty manner (taking turns at an aggressive pace, accelerating quickly, et.c) but sometimes I want to go all-out like when I am accelerating from a tollbooth and I want the car to just respond the way it should...not via the push of a button or whatever.
Oh yeah, and the new 6-Series looks good !!