I read that GM’s CEO approved a redo of the Malibu (at least front and rear fascia) to be implemented ASAP. I’d duck my head low for a year or so if I was the designer of the 2013.
They may not have had production MKS’s available - could be a polished up pre production (I used to watch them do teardowns on a dozen crash cars @ GM and end up with one car that looked great for photos / promos / shows).