Yes, there is a difference between what you will run on averge or "all day long" and what's "possible" with the perfect run on the perfect day on the perfect track.
I read about one of the tuners that tested their new automatic stock and got 13.03 backed up with 13.02....impressive. I think it will probably do 13.1 - 13.2 all day on any given day, but as for how fast is possible....Well, keep in mind that it was a new car and that automatics don't come with the sticky Perreli summer tires. So considering that and the 3:15 rear gears, 13 flat is impressive. They said it spun so bad with the hard stock tires that they just took off from idle and eased into it. Every time they tried to rev a little and let of the brake and go, it just spun too bad. I also read another automatic review and the guy didn't get any times but said it spun the tires like crazy on take off.
Now, with all that said, I think when the car is well broken in, say 10 to 20 thousand, it will go 12's on a good day. Throw some summer perrellis like come with the
Brembo package and you will be solid 12's. Drag radials may get you as low as 12.5 or 12.6. Evan Smith went 12.3 on nothing but drag radials with a standard so this sounds reasonable for an automatic. SCT tunes are getting 31 peak rear wheel horse power for automatics and as much as 50 horsepower at points below the peak. That should take three tenths off the quarter so now we are around 12.2-12.3 for tires and tune ( it may get more as it will probably increase the speed of the shifts as well. Add some 3:55 or 3:73 gears and you should get 11's.
I am thinking about an automatic so I've been trying to follow closely. I'm not sure if it will do it or not, but looking at the math it seems reasonable that you could got 11's on tire, tune, and gear......that's incredible to me.
But back to the original posters question, no you won't be dissapointed. Let it get broke in and if you are set on twelves, get some drag radials or maybe just some softer summer tires like the Perrellis and it should do it all day long.