From Wikipedia:
Duel is a 1971 television movie about a motorist (played by Dennis Weaver) on a remote and lonely road being stalked by a large tanker truck and its almost unseen driver. It was the first feature film directed by Steven Spielberg and was written by Richard Matheson based on his own short story.
Plot
David Mann (Dennis Weaver) is a middle-aged businessman driving to an appointment in his Plymouth Valiant. On a two-lane highway in the California desert, he encounters a faded and grimy tanker truck, a Peterbilt 281, traveling slower than the speed limit and expelling thick plumes of diesel exhaust. Mann passes the unsightly truck, which promptly roars past him and slows down. Mann passes the truck a second time and is startled when it issues a long air horn blast.
Mann soon finds himself in a bizarre cat-and-mouse game with the truck, which follows him into a gas station and begins tailgating him once the vehicles return to the highway. After Mann allows the truck to overtake his Plymouth, the truck slows and soon begins blocking Mann’s path each time he attempts to pass the truck. At one stage the truck driver waves at Mann, indicating that he can overtake, but as he does so he almost collides with an oncoming vehicle. Mann discovers an unpaved turnout next to the highway and uses it to race ahead of the truck. The truck pursues Mann again, this time chasing him at speeds of over 90 miles per hour (145 km/h) down a mountain road and bumping him several times until the Plymouth goes off the road in front of a diner.
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