ending: an old Native American man pours a line of powder across a desert highway and the haunted, devil car or truck crashes into an invisible wall where the line of magic dust is. late 70s, it think. i've been scouring the 'net and racking my brain trying to figure it out. "The Car" sounds close but i don't think that's it. i don't know why i don't ask you guys first when i have a question like this. you seem to know more than any search engine or film site. thanks.
Shadow of the Hawk, 1976. Starring Jan-Michael Vincent as a magical Indian.
thanks mbi, votes of gratitude coming your way. i've looked around a little bit, and finding a copy looks like it's gonna be way harder than figuring out the title.