The Nissan Leaf is a medium-priced electric car sold in North America. Compared to other cars of a similar size, it has very few closed storage spaces - the glove compartment is very small, for instance. The cargo space behind the rear seats is open to view. Nissan makes a cover, but it is an optional accessory and retails for about $150.
I made one from hardboard for about $15. The only complex thing about it is the shape.
The cover is 45 inches across and about 21 inches wide; it can be cut from a 4 foot x 2 foot piece of hardboard. I added a stiffener of half-round wood along one edge, glued and stapled, and a second shorter piece on the other side (hidden in the photo).
The shape to cut is in the PDF file. If you get a large piece of cardboard, you can make a test template before cutting the real material.