What is this thing below the back seat?

[atikovi]

Some kind of strap that slides in a groove.

 

[araxara]

It’s a cup holder! Slide the buckle and the leather strap will open and then you can secure a cup by sliding the buckle back.

I had this on my 2012 Model S. It was a $70 accessory. I only used it a few times. If you hadn’t posted this picture, I would have never remembered it again.

 

[atikovi]

OK thanks. So instead of spilling your drink into an easy to clean cup holder, it's spills on the harder to clean carpet? Great idea. The back of the center console is 12 inches away. Why not there?

 

[zoomer0056]

The back of the center console is 12 inches away. Why not there?

You can spill your drink wherever you like.