That slot is for the bumper jack to lift the car to change a flat. My grandpa's Chevy had it. And now that I look at it again, I think it doesn't look good. Don't get me wrong, I used to love my grandpa's Chevy, but little slot doesn't look cool. I know, I understand the purpose, and you avoid ruining the car, but I don't know....Back in the day all cars came with a ‘finger pincher’ in the trunk. These slots are where this attachment.. So, please SHARE if you remember this feature in the cars.....