I went through the same search a few months back because I needed something waterproof that still let me clip my dog’s harness into the seat belt properly. One thing I’d definitely recommend is looking for covers with zippered seat belt openings rather than just loose Velcro gaps, they stay in place much better once the dog starts moving around. I ended up pairing a heavy-duty rear seat hammock with a proper harness from Supreme Dog Garage, and that combo has worked really well on longer drives. The harness attachment lines up cleanly through the seat cover openings, and the back seats stay protected even after muddy walks. Also agree with the earlier comment about reinforced stitching on the straps, cheap ones tear surprisingly fast. If you’ve got a larger dog, side flaps on the cover are worth having too. They save the door panels from scratches and wet fur more than you’d think.