Even before DUEL, Spielberg made a little horror film called SOMETHING EVIL (1972), which starred Darren McGavin (just prior to his NIGHT STALKER stint), Sandy Dennis, Ralph Bellamy, and Johnny Whitaker. It was a made-for-TV flick, and was downright terrifying to me as a kid. Watching it now, it still holds up as a very effective film, if not quite as scary as it was when I was 13.
It occasionally runs on the Flix movie channel, uncut. I recommend it highly if you get a chance to watch it.