TOKYO (AP) -- Honda's new hydrogen-powered vehicle, set for leasing within a few months, radically reduced the sizes of its fuel cell and motor for a superclean car with the same interior space as a regular car, engineers said Tuesday.

That's a vast improvement from the company's first such model introduced nearly a decade ago. The fuel cell was so bulky that the car could barely seat one person -- and crept along at a snail's pace.

The new FCX Clarity reaches maximum speed of 160 kilometers (99 miles) an hour and comfortably seats four people.

''This is the ultimate in cars,'' said Sachito Fujimoto, a head engineer at Honda who oversaw the new fuel cell's development.

Clarity, unveiled at the Los Angeles Auto Show late last year, was shown to reporters at Honda Motor Co.'s Tokyo headquarters.

The garnet-colored, low-slung sporty sedan is set for leasing in California this summer at US$600 a month, and in Japan this fall at a yet undisclosed price. Clarity is an improvement on Honda's current fuel-cell vehicle, available for leasing in Japan and the U.S. starting in late 2002.

The main improvement came from a design breakthrough in the fuel cell stack, which is the unit that powers the vehicle's motor. Inside the fuel cell, hydrogen in the fuel tank combines with oxygen in the air to produce water. A fuel cell vehicle does not produce any of the noxious fumes or gases linked to global warming.

Clarity also delivers two to three times the fuel economy of an equivalent gasoline-engine car.

The car's fuel cell stack weighs 67 kilograms (148 pounds), about 30 percent lighter than the previous model at 96 kilograms (212 pounds), and a third of the size of the unit in Honda's first fuel cell vehicle, in 1999.

It's small enough to sit between the driver's and passenger's seats. In previous models, the fuel cell was at the bottom of the car, making for a clunky appearance.

Another innovation in Clarity is its lithium-ion battery, now more commonly used in laptops and other gadgets, but a rarity in automobiles.

Hybrid gas-electric cars, like Toyota Motor Corp.'s popular Prius, use a different kind of battery, and Honda's previous fuel cell vehicle did not have a lithium-ion battery.

Worries have been growing about the safety of lithium-ion batteries since reports of laptops catching on fire, resulting in a recall of millions of batteries in recent years.

Honda engineers said the battery in the Clarity won't get as hot as those in gadgets. Clarity's battery helps in powering the fuel cell vehicle by storing energy produced when it slows down, adding to its efficiency.