It’s hard to think about the planet when you’re hurtling across it at 150 mph. Yet recent auto shows from Geneva to New York have unveiled concept sports cars that pursue power in hybrid, hydrogen, ethanol or diesel form. Are these sincere attempts to ease global warming or merely cynical bids to capture the PR lightning of the all-electric, 0-to-60-in-four-seconds Tesla Roadster? George Peterson, the president of industry analyst firm AutoPacific, says that major luxury manufacturers are developing high-performance green tech with a wary eye toward future regulation of carbon-dioxide emissions. Not to mention meeting the proposed 31.6mpg U.S. standard by 2015. But many companies, he believes, are merely trying to attract image-conscious investors and buyers. “They’ll sell so few cars that the environmental impact is almost nil,” he predicts. “It’s mostly about bragging rights.”

Let the boasting begin. Launch our slideshow of the the fastest and flashiest eco-conscious sports cars, along with the odds that you’ll actually see one blow you away at a stoplight.