There are two different "cargo mats" on the official chevrolet accessories list. One of them extends up the back side of the rear seats and is called a "cargo liner". When the rear seats are folded down, there is additional protection against damage from whatever cargo is placed across them. I'm intruiged by this, and curious about the attachment mechanism to the back of the seats.
This is the more conventional cargo mat:
Premium All-Weather Cargo Mat in Jet Black with Chevrolet Script
Part No. : 42669376
This is the extended cargo
liner:
Integrated Cargo Liner in Jet Black with Chevrolet Script
Part No. : 42750492
Weathertech has also released an aftermarket
cargo liner, and I've had good use out of these on other vehicles. I especially like the high lip on the weathertech liners, although I find that they don't stay put as well as I'd hope (true for most cargo mats, IME).