My June 2015 car has slots in the cover so it's been a while now
That's good to hear Phillip as still waiting for mine to be built. I was just reporting on what I saw on a 2014 and possibly early 2015 model. When I placed my order recently the dealer mentioned the spacers but not the slot.
Guess any water that comes in through the slots is free to drop out of the cover courtesy of the spacing washers.