Movie about post apocalyptic semi truck where the truck is in desert going toward a town and the town people hear the truck comingand they hide in an underground shelter. The truck makes a whistle like a turbo and the people hear it from a long ways away.

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Warlords of the 21st Century (released in some areas as "Battletruck") would be my best guess. Did the good guy ride a motorbike?

http://uk.imdb.com/title/tt0084887/