I bought the OEM 2012 Hatchback Cargo Mat rather than wait for a specific mat made for the Plug-in, as I don't want to risk getting the carpet dirty or stained in the meanwhile. The fit isn't exact, but very close. There is an area on the right fenderwell where the mat won't quite lie flat, which doesn't bother me. But if that would keep you awake at night, you should probably wait for one made for the Plug-in.
I've got one issue with hatch mats: flip down the back seats and there goes your fit, LOL. With various cars over the years I spread a cheap blanket over the area. More flexible.
I rarely have had the need to lower the seats over the last eight years with my two Gen IIs, but have used a plastic tarp for those occasions. My concern is more for day to day stuff from the grocery store or the nursery. No matter how careful I am to put down the plastic sheets they give you at Home Depot, I manage to get planter mix or fertilizer shifting down to the floor. Oh, for the days when I had a truck for that kind of thing!
