Kurgo Seat Belt Tether Carabinar

This dog seat belt attaches to your dog's harness with a carabiner and clicks directly into the female slot of any car's seat belt, making it quick and easy to restrain your pup to avoid distracted driving.

Buy another seatbelt tether, and whamnow you've got two. The exact same number of cars you have. Wait, what's that? You actually have three cars? Math still has you covered: just buy two more. POW. Math could do this all day.