Green's been in the air of late, and this year's North American International Auto Show was no exception. While the usual hyped sports cars and solid trucks weren't exactly in short supply, nearly every concept car toed the eco line. Fuel cells, biodiesel and batteries powered most. Ethanol was popular despite continual rumors of a looming corn shortage (probably less of a problem in the "conceptual" realm). Even Hummer promised a FlexFuel system for its HX concept. Of course, none of this means power will be sacrificed. Ferrari introduced green concepts too; and you'd better believe they're not going to be slow.