I buy stretchy fake fur, cut a newspaper pattern, then cut out the fur with large seam allowances. I make a casing and run good elastic through the casing and pull it tight. The covers usually fit like a glove and they wear like iron. I have made covers for all but 1 of our past cars.

Some years ago I made terry seatcovers for my car, and they felt and looked so much nicer than the vinyl seats. I measured the widest part of the seatbacks, all around, then bought on sale towels that were at least 2" wider. Draped a towel over the seatback, making sure I had a few inches to tuck into the bottom; pinned together to make a fitted envelope, then sewed that seam and turned inside out. For the seat decks I folded a towel in half for longer wear and extra cushioning, measured for where to add elastic, and sewed on a piece long enough to fit below the cushion. Added cloth tabs with a large hook and eye to go around the back of the seat to hold it on. They lasted several years, and easily came off for washing. I did not trim the extra fabric from the seams to avoid loose terry crumbs. Towels were less costly than yardage, easier to work with, and came in colors to match or coordinate with car interior.

I made another set using two towels for the seatback, so could use narrower towels and also have the "envelope" extend all the way down the back; it stayed in place better and cost no more because of the smaller size/cheaper towels.

I'd use denim or upholstery scraps....would be a bit more durable.

Just a FYI if you do a search and you get something you definitely want to rule out (like baby seat covers)you would put a minus sign in front of what you are trying to avoid.

"How to Make Car seat covers-baby"

Hope you share what you come up with when you make them.