A growing number of Steve McGreens are souping up their gas-electric hybrids to make them go faster and handle better, while delivering stellar fuel economy. It isn't just gearheads busting their knuckles, either. A lot of the hybrid hackers are tech geeks whose innovations may well appear in the cars we'll buy tomorrow.

"The gearhead of today has evolved. People today want performance and fuel economy," Paul Goldman, the 46-year-old CEO of the hot-rod hybrid shop Juiced Hybrid, tells Wired.com. He sells more than 500 items ranging from suspension kits and chassis stiffeners to body kits and floor mats. Most of his customers are "educated people who care about the environment" and modify their cars "because they're tech savvy, not necessarily because they're car savvy."