NEW YORK (AP) -- Capping months of speculation about his mysterious innovation, an accomplished inventor unveiled the device Monday -- a one-person, battery-powered scooter that he claims will revolutionize transportation.

Kamen and his backers have big hopes for the agile Segway Human Transporter, saying the scooter will displace awkward, polluting cars, leading to a realigned cityscape that is more people-friendly.

The Segway, until now known only by its codenames "IT" and "Ginger," "will be to the car what the car was to the horse and buggy," Kamen boasted to Time magazine for Monday's edition. "Cars are great for going long distances. But it makes no sense at all for people in cities to use a 4,000-pound piece of metal ..."

Kamen revealed the scooter on ABC's Good Morning America on Monday. ABC's parent company, The Walt Disney Co., has sponsored Kamen's robot-building competitions for students.

Kamen and the morning show's hosts took the scooter for a spin in a New York City park, demonstrating various maneuvers and cruising up and down ramps as crowds watched.

"It just does it very smoothly, very gracefully ... What used to take you a half an hour will take you 7, 8, 9 minutes," Kamen said.

Kamen holds roughly 100 U.S. patents. His other inventions include the heart stent used by Vice President Dick Cheney and a wheelchair that can climb stairs.

Kamen said the battery-powered device requires little electricity. Kamen's Manchester, N.H.-based firm DEKA Research and Development will oversee production of the machine.

The two-wheeled Segway, which looks like a cross between an old rotary lawn mower and a Razor scooter, travels at a top speed of about 17 miles per hour.

According to those who have ridden it, the scooter is difficult to fall from or knock over due to gyroscopes that work to keep it upright and discern where the rider wants to go. Speed and direction are controlled by the rider's shifting weight.

Riders stand upright, facing forward over the invention's single axle, navigating with a bicycle-like handlebar. A single battery charge can propel the scooter 17 miles over level ground, with each hour of charge providing power for two hours' use, Time reported.

"All the knowledge that went into knowing how to walk is transferred to this machine. When you stand on this machine it kind of walks for you," Kamen said in revealing the scooter.

The U.S. Postal Service, General Electric and National Parks Service will be the first customers to purchase them, buying 80-pound heavy-duty models for $8,000 apiece, according to the magazine.

The Postal Service plans to test 20 Segways on mail routes in Concord, N.H., and Fort Myers, Fla., starting in January, in hopes of enabling carriers to cover more ground, according to a report on The New York Times' Web site.

The City of Atlanta plans to use several dozen starting in February in an effort to reduce emissions and traffic congestion, the Times said.

A 65-pound, $3,000 consumer model won't be available for at least a year.

Kamen, who said he withheld information on the Segway until he had finished filing related patents, is an accomplished inventor and recipient last year of the National Medal of Technology, awarded by President Clinton. Kamen's previous inventions also include the first portable kidney dialysis machine.

From the time plans for the machine were first leaked to a Web site called Inside.com almost a year ago, tantalizing but vague mentions of the project kept the device in a controlled state of pent-up hype. Corporate luminaries who'd gotten sneak previews described the machine's impact as "as big as the PC" and "bigger than the Internet."

Others have labeled the invention as a bunch of hype.

Time said its article's author was given license to shadow Kamen for three months, on condition of secrecy. Other publications, including the New York Times, were given advance information on the project in return for pledges to secrecy.

The Associated Press was offered an advance look at the invention on condition it did not release the information until an hour before the Good Morning America broadcast. It turned down the deal.