according to car&driver, the auto is faster than the manual in 0-60 and 1/4 mile. here's the link:
click here!
Automatic
Zero to 60 mph: 4.6 sec
Standing ¼-mile: 13.1 sec @ 108 mph
Manual
Zero to 60 mph: 4.8 sec
Standing ¼-mile: 13.4 sec @ 107 mph
from what i've seen in other threads, a lot of manual owners refuse to believe this and claim the manual driver sucked. or they try to justify the manual is better somehow because it has a clutch and sports cars are supposed to have manuals. this is the only test (that i'm aware of). until anything else is released, i will continue to believe this. i test drove both and got the auto because it's just as fun to me (don't really care to push the clutch pedal) - the paddles still kick nicely, and when i'm feeling lazy i just pop that puppy in "D". the manual is nice too. get what you like. at the end of the day you wont ever be the fastest...
edit: when someone says something is more "fun" than something else, it is subjective. thats why i recommend you try both. good luck.