I recently bought the second mainline Hot Wheels version of the Batman: Arkham Knight Batmobile. (I blogged about the first mainline version here.) The 2015 version is in matte black; the 2016 version is in metallic dark gray.
I found it in the hidden compartment at the bottom of a display stand, where most Batmobiles here can be found. Perhaps I should call this hidden compartment the Bat Cave.