I refer, of course, to the cup holders indentations that used to(?) be on the inside surface of glove box/compartment doors. The one pictured here is from my 1978 Mustang II and I can say almost for a fact that they have never been used for their stated purpose on this car. But my family had a succession of 1960s-70s domestic sedans and all of them had the ubiquitous "cup dimples" for lack of a more formal term (cup holder seems generous in the extreme). As a kid I recall maybe attempting to put some sort of beverage on them but it just never seemed to work out right. Either the door was too shallow and anything but a tiny little teacup would hit the top of the compartment, or whatever cup I was using wouldn't even fit in the dimple.
Suffice it to say, these things have been irritating me to some small degree for much of my life. I mean, it's not like I wake up every morning and cry to the heavens "Why, oh why are there useless dimples in my glove compartment door?". But it has been percolating in the back of my mind, lo these many years. And now, since I have this forum where all the world may partake of my (admittedly minor) little neuroses, I may possibly generate some answers.
Actually, when I started this post it was purely out of some other, related, irritation which we shall get to in a moment. As a matter of fact, when I started searching for these things in the ol' Interwebs I was a bit flummoxed on what even to call them. I came up with "cup dimples" on the fly, but I've also seen them referred to (once) as "picnic cup holders" but nothing else (admittedly I only flipped through the first two pages of Google results).
Am I the only one to find these things somewhat inscrutable as to their actual utility? I bet not.