Johnathan Goodwin walks to the back of his auto conversion shop in Wichita, Kan., and lifts up a gas nozzle connected to a huge cube-shaped container. He aims the nozzle at a clear plastic cup and squeezes the handle.
Out pours an orange-colored liquid that looks like a cross between iced tea and fruit punch.
"I always think when I'm pumping this stuff," said the 37-year-old, self-taught mechanic, "man, is this good for your motor?"
Watch David Kerley's report on Goodwin tonight on World News with Charles Gibson.
It better be. The orange stuff he's pumping is the key to his company's mission: converting the worst gas-gulping SUVs into cleaner, meaner machines.
"This is 100 percent canola oil, refined to biodiesel," Goodwin said.
His well-maintained shop is a bit like a showroom for that much-maligned symbol of environmental ruin: the Hummer.
Oddly, the brick walls of this shop that converts Hummers and other SUVs to run on cleaner alternative energies are dotted with nostalgic old signs for oil companies like Texaco and Mobil gas.
In one room, a bright yellow Hummer H-2 sits flanked by a silver H-1. Parked on the other side is a fire engine-red H-3 model owned by "Home Improvement" star Tim Allen. All the cars he shows off have been — or will be — converted by Goodwin and his team.
The silver H-1 — which Goodwin says gets 60 miles per gallon — has already been modified to run on biodiesel, diesel, vegetable oil, gasoline, ethanol, hydrogen, natural gas and propane.
"Pretty much anything that you want to put into it," said Goodwin, the owner of H-Line Conversions.
On a standard gasoline-to-biodiesel conversion, Goodwin starts by taking a new nine-mile-per-gallon Hummer and removing the original gas engine. In goes an off-the-shelf GM Duramax engine that runs on diesel fuel.
A few extra modifications and a tank full of biodiesel later, the Hummer — now boasting 500 horsepower and getting about 20 miles per gallon — is ready for the road.
"We double the fuel economy, we double the horsepower and we double the life expectancy of the drivetrain," Goodwin said.
It isn't cheap. A typical conversion costs about $35,000, allowing automakers to dismiss Goodwin as an experimenter who is only serving a narrow segment of wealthy car enthusiasts.
In response, he offers a couple of lower-cost options, including a fuel vaporizer for $1,000 that he says boosts fuel economy by 30 percent, and a $500 software download that reprograms diesel engines to get up to an additional seven miles per gallon.
His work has many wondering why the big automakers can't simply reconfigure their assembly lines to make their own cars run as efficiently as Goodwin does.
"I don't know why GM hasn't done it," says Goodwin, who figures he'd be out of business if they did. "But I can tell you that all the parts that I use for the conversion — 95 percent — are all GM parts. I'm not reinventing anything."
Automakers say bringing a new vehicle concept through the stages of design, testing, government certification and manufacturing typically takes eight or nine years. And they argue that simply building cars the way Goodwin does is not yet practical enough to be affordable to consumers.
"Taking an engine from one vehicle and putting it into another is not new," said Allen Schaeffer of the Diesel Technology Forum, an auto industry group. "That's kind of a shade-tree mechanic kind of thing. And that gets to be very complicated when you start thinking about things like warranty and overall performance."
But at the same time they dismiss Goodwin, automakers are paying attention — touting new diesel models soon to hit dealer showrooms.
"We expect that within the next year you're going to be seeing three more choices of pickup trucks from the Big Three manufacturers," Schaeffer said. "They're pushing the envelope on technology as well."
Goodwin, meanwhile, is excited about the future. He has a steady stream of customers and new-found celebrity in the automotive world, thanks in part to a 2007 episode of MTV's "Pimp My Ride" in which he modified a 1965 Chevy Impala that beat a Lamborghini in a drag race. While taping the show, he met California Gov. Arnold Schwarzenegger, who asked Goodwin to convert his 1987 Jeep Grand Wagoneer to run on biodiesel.
Now, Goodwin and singer Neil Young are converting the rock legend's white 1959 Lincoln Continental to run on hydrogen and electricity. A few days ago, he and Goodwin took it on a spin around Wichita.
"This is my hot rod Lincoln right here," said Young, proudly. "No emissions. No emissions ever. No matter how far we go, just going on electric or the generator, there's nothing coming out of the tailpipe."
Young is making a documentary about the car — dubbed the "Linc Volt" — and he and Goodwin plan to enter it into the upcoming Progressive Automotive X-Prize competition.
Being "green" is a bonus for Goodwin, who also tinkers with everything from cell phones to toasters. He laughs when asked if he's an environmentalist.
"I don't know what an environmentalist is," he said. "I just try to fix problems. I'm a good fixer of things."
In the end, Goodwin says the most important thing to fix is inefficiency.
"Everybody is worried about what fuel source is going to be the next hot seller," he said. "And I'm saying we need to focus on creating vehicles that are more efficient. I don't mind seeing $10-a-gallon gas when I have a 200 mile-a-gallon vehicle."
ABC Wichita affiliate KAKE-TV contributed to this report.