Here's the scoop on the silver Camaro from the SEMA showfloor as seen HERE
and which everyone speculated as the Camaro Z28 due to its bumper's similarity to the look of only model mockup PHOTO
we have seen of the Z28.
This car is a V6 twin turbo Camaro built by GM (hence its location in GM's Camaro display at SEMA). The turbos used on the V6 motor are turbonetics turbos.
GM design worked with Jay Leno on the design of this car, and the car is labeled "inspired by Jay Leno."