twin snail 4.4L

Bought a new 550xi Saturday evening. Had been looking at 2011 535xi and 2010 E550s for my wife. Spent a couple hours Wed looking at 550xis and was told by the first dealer that I would not be able to touch a 550xi for anything less than 70s, so went to another dealer in StL and test drove a grey 550xi. I was immediately sold on the car and agreed on a price slightly below invoice inluding rebate and transportation costs "from up north." Car is Jet Black with black dakota leather, and Pkg I and II, with smart phone integration. Car has 10 miles on it. This car is coming in Friday night and will be ready for pick up Sat AM. My wife and I live an hour outside StL and had planned on going to StL for a cooking and wine pairing class. I am more about eating and drinking,,, anyhow the couple we will be spending the weekend with, drive a Black 09 M5 with the V-10 and 6 sp manual. Should be a propper ride to pick up the 550. Its going to kill me to park that car in a hotel parking lot the first night of her short life. After trolling this board, I am regretting not getting the sports auto with paddle shifters. Whats the difference, shift points, any other differences? What kind of performance gains am I giving up? .1 to .2 sec 0 to 60 and in the quarter mile?????
This is my wifes daily driver. My daily is a 6 spd CTS-V. I have a highly modified 30,000 mile Buick Grand National and a Stage II H/C C5 corvette with 6 spd and 3.90s. I like fast cars and this one feels like a runner. My guess is that its under-rated by BMW, definitely is when guys are running 12.9 @ 109mph in a 4350# car. sounds like it is getting decent milage for a performance car. Look forward to learning on this forum. I have been a fan of the 5 series since my GN was a regular driver. This is heads and tails the best 5 series yet.