Check out this article, the ZL1 will use the 6L90E auto transmission.
http://www.autoweek.com/article/2011...NEWS/110909865
from the article:
Likewise, he stressed that the optional six-speed Hydra-Matic 6L90 automatic gearbox is “not for poseurs who don't know how to shift.” As a general rule, hard-core enthusiasts will choose the six-speed Tremec manual transmission, but at least the auto 'box is built for performance, with three different driving modes including a manual setting that only shifts when a driver commands. Automatic upshifts will not occur even at redline, and Oppenheiser promised that it will select and hold the appropriate low gear into corners to match the manual-equipped ZL1's performance.
“Contrary to what we could have done [by taking the easy way out with a simple, off-the-shelf transmission], the automatic is not a compromise,” he said. “We spent a lot of time working on it for the track.”
And they are already used in the Cadillac CTS-V.