This piece from the Gothamist lists some actual Drive In Movie Theaters that still exist today close to New York City.
I have fond memories of the Langley Drive in Theater close to Vancouver BC. I remember seeing E.T. there and a few others. Usually they were double bills.
I also remember motels along the highways in BC would have large outdoor screens where you would watch the movie from your motel window, and tune the radio into the soundtrack. Very bizarre.
It's a concept that some people born after a certain year will have no idea that these existed.
Sure environmentally it's probably terrible, but it was a fun time. I'm sure it's a trend that can resurface again at some point, seeing they are doing regular outdoor cemetary screenings at the Hollywood Cemetary now.
Film Dweeb Link: http://goo.gl/Rw3GA3