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."

Like all automotive trends, hybrid hot rodding started at the grassroots with green gearheads wrenching at home. But it's entered the mainstream, with big-name builders like Braille Battery bringing big-budget hybrids like the 440-horsepower "Hot Rod Hybrid Altima" to the annual Specialty Equipment Manufacturers Association auto industry trade show in Las Vegas. As the number of automakers producing hybrids grows and the number of people buying them explodes, SEMA officials say, so too will the number of people demanding go-fast goodies for them.

"The green performance revolution is well underway," says John Waraniak, SEMA's VP of vehicle technology. "Bringing more environmentally friendly, responsible-vehicle technologies and products to the marketplace doesn't mean that you have to sacrifice performance and the coolness factor."

Arah Leonard was among those who didn't want to sacrifice performance when he picked up a Toyota Prius, so about a year ago he started asking the guys at Priuschat.com for advice about modding his ride. Leonard says he wanted to "show the world that hybrid doesn't mean a slow car."

He aimed high, hoping to make the Prius quick and nimble enough for autocrossing. Turns out he didn't have the time or the money to make it happen – never mind that the Prius isn't designed for racing. Its gas-electric drivetrain, regenerative braking and traction control "make for an incredibly bad racer," Leonard tells us. All the high-tech hardware "makes autocross racing rather ... disappointing. You just can't power-steer through a turn."

That's not to say people haven't raced hybrids with varying levels of success. This YouTube video shows someone putting a Prius through its autocrossing paces. A Japanese gearhead pushed a Prius to 135 mph at the Bonneville Salt Flats a few years ago. The British team that has rally raced a Honda Civic Hybrid is developing a hybrid for road racing. German boutique supercar company Gumpert ran an 800-horsepower hybrid at the 24 Hours of Nurburgring endurance race, and Peugeot says it will bring a hybrid to Le Mans. Many of these cars bear little resemblance to the hybrids you'll see outside Whole Foods, but it's only a matter of time before the technology trickles down from the race track to the showroom.

Of course, most people who hack their hybrids aren't so ambitious. Goldman says most of his customers – the majority of them drive a Prius, and nearly half of them are women – simply want to make their hybrids look and handle a little better. "They buy a spring set, EV mode and a body kit," he says. A thriving online community of modders provides noobs with the support to tackle big jobs, Goldman says.

"If it's documented well, they'll do it," he says of budding eco-modders. "I have people who have never worked on a car engine before taking apart a direct injection."

The most ambitious hybrid hackers were converting their cars to plug-in hybrids long before there was a cottage industry to do the job, and they're years ahead of Toyota and General Motors in getting these super fuel-efficient wonders on the road. Of course, the major manufacturers frown on people second-guessing their engineering, and some mods may run afoul of emissions regulations and void your warranty.

But hot rodding has never been about following the rules. People have been modifying cars almost as long as automakers have been building them, and no one expects that to change.

"We have this emotional response to automobiles," Goldman says. "We can even get a better experience with a hybrid because you're helping the environment and you can have some fun with it too."

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Main photo by Braille Battery.

Race car engineering firm Braille Battery turned a sedate Nissan Altima hybrid into a 440-horsepower tarmac terror. The car sports a a supercharged E85-burning engine massaged to produce 270 horsepower; it's mated to a synchronous electric motor. Just about every part of the car, from the drivetrain to the suspension to the brakes, has been heavily modified. Yeah, it's extreme and bears almost no resemblance to the Altima Hybrid you'll find in a showroom, but it shows what's possible. Photos by Braille Battery.

*Most modified hybrids are more along the lines of Paul Goldman's Prius. The owner of Juiced Hybrids installed a body kit, bolted on a set of alloy wheels with sticky tires and made other mods to trick out a sportier Prius. *Photo by Paul Goldman.