We used a pick-up truck with our kids. Piles with blankets and pillows and stuffed animals. Good times. I see the two that we went to are gone - but there are still five of them “near” us - on the west side of Puget Sound. Although I’m not sure my wife would be up for such a late night. (And I don’t really care for the movies anymore!”)
I didn’t know there are still ANY drive-in theaters open. Glad to hear otherwise! I had really assumed none remain, because none of those I grew up with survived past the early 1980’s.
If I use Google satellite maps and Streetview I can find faint traces of them in the landscape, pieces of the old signs still sticking out of the ground or something like that. Stuff that would never be noticed by anyone not specifically looking for it.