One day, young Sincero McHeartfelt decided that he needed a cause, so he bought a diesel van, fueled it up with used cooking oil and drove around the greatest country in the world, talking to people like Neil Young and Willie Nelson about the wonders of biofuel. And he talked persuasively, because these people, and other stoners, like Woody Harrelson, heard his words and converted their ways. Then 6,000 newspapers drew some illicit conclusions from two articles in Science magazine, and the biodiesel industry fell apart. And then Sincero did what all good activists do these days: He made a documentary. And you can watch it, if you can handle a lot of earnestness, an attention-deficit-disorder style, and too many emotive moments. What you’ll get is a lot of information which, if you’re smart, you’ll follow up on, and maybe you’ll even change some of your energy-consumption habits. What you won’t get is a terribly well-made film. Oh, it’s slick and highly produced; it’s just loaded with too many standard documentary tropes and a poor sense of focus. But it’s important, and “important” is written in beautiful flowing calligraphy by a first-year student at a liberal-arts college in Vermont.