I'm not saying no one has ever thought of this before, but recently I discovered something that makes it much easier to carry groceries in the hatchback of my car without having my reusable bags fall over and dump stuff all over the place.
As with many useful discoveries, it happened by accident the first time and I couldn't help but notice how well it worked out.
It's ridiculously simple: just arrange your bags along the sides of your hatch area and drape the handles over the edges.
Then shut the hatch so that the handles are caught in the hatch door.
The bags are held upright throughout the drive home and nothing can fall over or out, even if you take a sharp turn or brake hard.
Obviously you'll need to decide whether you want your bag handles getting wet if it's raining or snowing, but otherwise I think it's a pretty neat trick.