Hey folks,
Thought I would throw in my experience. I have a 2013 Rio 5 SX, built June 2012. I do have the tray in the trunk. It is cheaply made and fairly shallow. It is the width and depth of the trunk area, but about 7~8cm deep. It barely holds a few tools but nothing too big. It sits under the trunk floor panel but above the spare tire/jack.
I also have the cargo net. As others have mentioned, it ties down to four tabs on the trunk floor, two on each side. I originally thought that it was meant to be strung higher or two hold items against the back of the rear seats. Nope, it is meant to hold items down to the trunk floor and hopefully prevent sliding and shifting.
As for the "Metal-grain trim plates," not a clue. I have scoured the door trims and other areas but no luck. Then I realized it says "Metal-grain trim plates,” emphasis on "metal-grain" and not metal. This most likely means that it is metal-grain looking plastic trim, possibly the trim around climate controls and the shifter? Perhaps it is the trim around the instrument cluster? Unfortunately I don't have a lower model to compare it to but I'm guessing it might be something like this.
I'm curious if someone knows for sure.