You are thinking of the mid-range accelleration of the Porsche 928 S4 and GTS. That was the car that had quicker 60-100MPH accelleration, than its manual transmission version.
I'm not talking about top-gear roll-on, where an automatic cheats by downshifting, while a manual must stay in it's higest gear. I'm talking about a true test of accelleration, where the manual can be shifted at will. In that case, the only car I know of that had better performance with the automatic, was the 928 S4 and GTS. I am not aware of any Corvettes that were quicker with automatics, unless you are talking about modified drag cars.
I think you've ridden in a fairly rapid manual-transmission Corvette, haven't you? ;-)
-Sean