BTW, War is still touring. I saw them in concert a few weeks ago. And yes, they played "Low rider", last song, place went nuts. There were rumors that George Lopez owned the rights to the song, as part of his TV show, so the band couldn't perform it anymore.
Yeah i guessed Up in Smoke which did use the tune so seems like it needs to accept any correct answer or provide something that narrows it to a specific movie. But I like the idea.