I was looking for a cheap way to secure a shelf in my garage that still looked nice and came across this deal. Obviously, pet is not for what I'll be using them for, but I'm basically attaching the ring part on the wall and attach the hook to my shelf. This way, it's easily removable. Far cheaper than buying ugly looking stuff designed for this purpose, I think. Anyhow, I figured I'd share since this seems like a good deal for its intended use too. I don't have a dog right now, so maybe people who have used something like this can chime in how it works. I'm guessing that your car's buckles need to be compatible. Ships free with Amazon Prime or for an order of $25 or more.
Coupon code: TU9SHG6W (30% off)
4 x Adjustable Pet Harness for Car/Seat Belt [amazon.com]