It looks like an ordinary family sedan, costs more to build than a Ferrari and may have just moved the world one step closer to a future free of petroleum. The FCX Clarity on a test drive after an introduction ceremony in Japan on Monday. On Monday, Honda Motor celebrated the start of production of its FCX Clarity, the world's first hydrogen-powered fuel-cell vehicle intended for mass production. In a ceremony at a factory an hour north of Tokyo, the first assembly-line FCX Clarity rolled out to the applause of hundreds of Honda employees wearing white jump suits. Honda will make just 200 of the futuristic vehicles over the next three years, but said it eventually planned to increase production volumes, especially as hydrogen filling stations became more common. On Monday, Honda announced its first five customers, who included the actress Jamie Lee Curtis. Honda said even the small initial production run represented progress toward a clean-burning technology that many rejected as too exotic and too expensive to gain wide acceptance. "Basically, we can mass produce these now,' said Kazuaki Umezu, head of Honda's Automobile New Model Center, where the FCX Clarity is built. "We are waiting for the infrastructure to catch up.' Fuel-cell vehicles have been a sort of holy grail of the auto industry, offering the promise of driving without emitting air-polluting exhaust. Fuel cells work by combining hydrogen and oxygen from ordinary air to make electricity, in a process whose only byproducts are water and heat. They have drawn renewed attention in an era of climate change, $140 a barrel oil, and rising competition for dwindling fossil fuels. "This is a must-have technology for the future of the earth,' said Takeo Fukui, Honda's president. "Honda will work hard to mainstream fuel-cell cars.' Fuel cells have an advantage over electric cars, whose batteries take hours to recharge and use electricity, which, in the case of the United States, China and many other countries, is often produced by coal-burning power plants. Honda says its FCX Clarity can be filled easily at a pump, can drive 280 miles on a tank, almost as far as a gasoline car. It also gets higher fuel efficiency than a gasoline car or hybrid, the equivalent of 74 miles a gallon of gas, according to the company. But the technology has faced many hurdles, not the least of which has been the prohibitive cost of the fuel cells themselves. Honda says it has found ways to mass produce them, which promises to drive down costs through economies of scale. On Monday, it showed reporters its fuel-cell production line, which resembled a semiconductor factory more than an auto plant with its humming automated machinery and white smocked workers in dust-free rooms. Mr. Fukui said the cars cost several hundred thousand dollars each to produce, though he said that should drop below $100,000 in less than a decade as production volumes increase. In the meantime, the car company will be effectively subsidizing its customers, who will lease the vehicles for $600 a month. That is not much more than the leasing price of one of Honda's top Acura line of luxury cars. At Monday's ceremony, Mr. Fukui presented an oversize key to the first FCX Clarity customer, a film producer from Los Angeles on hand for the occasion. Honda said it would offer the car in Southern California first because the state has been a leader in building hydrogen filling stations. Honda said the five had been chosen after the company got a wave of queries from American consumers when it publicized the car last year. On Monday, Honda also announced three dealerships near Los Angeles that will be the first to start leasing FCX Claritys. Fuel-cell vehicles have been a big gamble for Honda, which has spent the last 16 years and millions of dollars