Do you have one of these things?
It’s a little fold-out container for your grocery bags. It helps keep them from falling over.
Okay, I see that the product description lists it as a “trunk organizer.” But I use it solely for grocery bags. Well, and one time I used it for seedlings that I was taking home to plant.
It falls under the category of “totally unnecessary but nice to have.” I have lived successfully without one for many decades. But my husband got one sometime last year, probably because his trunk is completely 100% empty, so things tend to slide around in there. (I do NOT have that problem.) But over time, I started getting envious of his little container, and – since I am the Primary Grocery Shopper of our household anyway – I asked him to buy me one, too.
(I could have bought it myself, you understand. But he likes to do Detailed Research on all things, which I do not care to do. Plus, he purchased the one for his car through his Amazon account, so I figured he could just re-order it. To make a boring and unnecessary aside more boring and unnecessary, the one he has was no longer offered, so he got me this one instead.)
I love it!
This is how it looks, all full:

There are four bags inside the trunk organizer, and then one (the big red zipped-up bag) that has to sit outside the organizer with all the other junk I have piled in my car.

Top view, which I see now looks like nothing but a jumble. You can also get a peek at my groceries, which included ALL THE PRODUCE.
My trunk is a mess. Someday I should clean it. To be fair, I cleaned it pretty recently. It’s just really hard to know what to do with some of the supplies I have back there. The jumper cables should stay, even though they are unwieldy and take up a lot of space. The bags have a variety of blankets and winter gear and emergency snacks and coloring books. I think there’s an old diaper bag in there, too; now that my child is FIVE perhaps I can finally get rid of that. (SOB!)
This is how it looks, without the groceries but unfolded:

The blue thing on the bottom right is the wing of a parrot paper bag puppet Carla made for me and insisted I keep in my car at all times. Like a talisman. That’s molting.
The trunk organizer has Velcro on the bottom, so it sticks nicely to my fuzzy trunk floor. And you can unfold only half of it, if you only need half. And there is a divider inside, if you need one large rectangle and two smaller squares, or just one or two smaller squares.
Here is how it looks, all folded up:

So small and compact! To allow room in the trunk for MORE JUNK!
Man, my trunk could sure use a good vacuuming. Let’s all ponder when that will happen, taking into consideration that it is fifteen years old and I cannot remember every having vacuumed it. Hmmm. Hmmmmmmm.
How funny – I was only looking at one of these in Costco recently and couldn’t quite justify buying it whilst at the same time wanting it quite badly!
As far as car cleanliness goes – whilst I love a clean outside it rarely actually gets washed at all regularly, but I can’t stand a mucky interior and vacuum at least three times a week! I’d be all over your boot!
Our trunk is so small the groceries fit snugly and we do not have anything rolling around. It is delightful.
But. My husband LOVES the process of doing research to purchase things. He has recently been researching athletic shorts with pockets to purchase and while I would basically just buy the first thing that met my requirements, he has been doing this research for days. He notes each pair that meets whatever his criteria are and then he compares them. This is too much work for me, but he loves it. People are weird.
My husband (the main grocery purchaser) asked for one for Christmas. I think I ordered the same one. He LOVES that thing.
As for car cleaning; yours looks positively spectacular compared to mine. This is the first, and last, time I will ever own a car with black interior…period. In order to keep it looking clean I would have to vacuum it every day – sometimes twice a day.
Ohh you don’t want to hear about the interior of my car and how infrequently it gets cleaned. A few weeks ago I spent $555 on groceries (that included lots of pricey over-the-counter acne medicine for teens, but STILL), so I don’t think a trunk organizer is in my future. It does look great.