Simple answer: Not everyone buys this car for the track.
Personally, I wouldn't drive the auto. That's too boring for me. Even with paddle shifters, it's still too boring. And the sport package is a good value, so you can add that on for me. And the touring is more comfortable with heated seats and Navi.
If I were going to build "the fastest straight line car possible", the Z wouldn't be my base platform in the first place.