I rarely buy into conspiracy theories but the idea that this has been technically possible as long as it has and it still isn't implemented on a far larger scale reeks of the big oil companies being in bed with the automotive industry.
Guys like this are slowly pushing this stuff out, but they're meeting resistance from a lot of different fronts. Like the aforementioned GM engineers who were told by their superiors that it couldn't be done.
I think the most telling part is this:
Goodwin's work proves that a counterattack is possible, and maybe easier than many of us imagined. If the dream is a big, badass ride that's also clean, well, he's there already. As he points out, his conversions consist almost entirely of taking stock GM parts and snapping them together in clever new ways. "They could do all this stuff if they wanted to," he tells me, slapping on a visor and hunching over an arc welder. "The technology has been there forever. They make 90% of the components I use."