In reply to elsewhere:
Not any help to you, but hope you don’t mind a bit of nostalgia and memories. I thought I would mention what I still use in the car. It’s a circa 1940s, original motorbike cover I was told, which I inherited. My late father used it on his motorbike, and after his motorbike it was used for many things and had a hard life before I got it.
It is padded, and thickly woven on one side, and a heavy duty canvas cover on the other. Originally the canvas was coated with something and was waterproof so would keep a motorbike dry and the padding was to protect the motorbike and to retain some heat in cold weather to help with starting. Long time now since the majority of the coating had disintegrated so not waterproof as all now.
It’s going strong for car/push bike protection. Robust still to take a bike frame and wheels being pulled and pushed over it. Laid on the boot floor and on folded down back seats it takes all the mud, water drips, oil drips or whatever from my bike when transporting. When it gets drips it just soaks the water in so boot carpet never affected. I just let it dry and with a shake of dirt off it’s good to go again. Stays in boot folded in half and cushions anything I throw in and stops things sliding about.