I don't know any drive-ins that just play old crap; i'd LIKE it, but i don't imagine it's commercially viable. Still, that's almost not in the spirit of the problem -- if you are under the impression that, somehow, drive-in theaters used to be bastions of cool once upon a time -- and not commercial establishments that, like today, would just do whatever it takes to make a buck -- you are living under a rose-colored sun of nostalgia-inflicted brain damage. But, yeah, that said, i DID see "Dawn Of The Dead" at a makeshift outdoor theater a few years ago, and it was AWESOME. But, that said, the nostalgia of, say, corded drive-in speakers is about on par with the nostalgia of, say, corded home telephones...i.e., not particularly appealing at all.
There is one outdoor theater about 20 miles out of town from where i live, and another perhaps 45 minutes away. I go to the closer one all the time in the summertime. Why the hell not, i got a sunroof.
The coolest outdoor theater i've ever seen was on the outskirts of Kansas City. It was called "The Twin," or something similar. It looked like it was straight out of Bedrock.
I used to go to drive-ins right at the very end of the original wave, in the early 80's. The movies were godawful, they were usually porn movies with the explicit parts cut out ((i.e., anything after boobs)). As such, they mostly drew high school kids and miscellaneous scumbags, who always seemed to want to fight at the concession stand, and every other god damn thing. That was cool in a way ((yes, i used to sneak in in the trunk)), but, honestly, my suggestion is that you just get a bunch of beer, drink it, and learn to appreciate Harry Potter on some level -- even if it's just the level of "it's nice out and i'm sitting in my car getting drunk and there's some lame movie playing." The movies that people nostalgically consider "drive-in movies" were, almost without exception, so mortifyingly lame as to beggar description. Take what is there and make it yours. Thank you and good day.