This is my third auto... 07, 13, and now '15. I am done with a clutch and rowing...(before that I had 7 mustangs w/ manuals)
So, now I have a base '15 auto w/ 3.55's. The sport mode shifting using the paddles is pretty cool, but I have only used a few times...but it is really a novelty. The car's computer can shift way more efficient than you can paddle it. The car drives really nice in both regular and sport shift mode. I really can't tell any WOT difference between the two modes.
Sport shift mode has the car shifting under normal conditions at around 2300 rpms... while in the regular D mode at around 1700 rpms.
One thing to note, the 3.55's in an auto is really too much gear and just causes you to spin more...If I had to do it all over again, I would have just gotten the standard 3.15's.
Maybe with a sticky drag radial at the track it might help, but it smokes the tires up instantly in 1st gear on the radials.
On a slightly cold day, w/ traction control off, the car will spin at WOT in 2nd gear... now that is crazy for an automatic stock car. But what the hell... I have been called crazy on the forum by most anyway...