Japanese auto manufacturer Honda launched the first commercial production of a hydrogen fuel cell-powered car Sunday in Tochigi, Japan, and said its first customers will be in the United States. The four-door sedan, called the FCX Clarity, runs on electricity from a fuel cell battery powered by hydrogen. Steam is its only by-product.    The car boasts a combined (city and highway driving) fuel efficiency of about 72 miles per kg of H2 which, according to Honda's own estimates, is the equivalent of getting about 74 mpg from a gas-powered car. It can be driven for about 280 miles before needing to be refueled.    While many automakers and researchers have prototypes and pilot projects using hydrogen fuel to power fuel cells on electric hybrids, or as a direct fuel source for vehicles with converted engines, there are no hydrogen-powered cars yet available for lease or purchase to the average consumer.   Honda claims it is the first company to have a hydrogen car certified for regular commercial use by the US EPA. The FCX Clarity was first introduced as a concept vehicle in 2005 at the Tokyo Motor Show.   "This is an important day in the history of fuel cell vehicle technology and a monumental step closer to the day when fuel cell cars will be part of the mainstream," John Mendel, executive vice president of American Honda, said in a statement.   Honda plans to offer the hydrogen-powered FCX Clarity through a lease program from one of three dealerships in California, starting this July. They will be available on a three-year lease for about $600 per month.   Among the first owners will be actress Jamie-Lee Curtis and her husband, filmmaker Christopher Guest. The biggest problem prospective owners are likely to face is where they can refuel, as there are yet only a handful of hydrogen fuel stations in California, and virtually none anywhere else.   *          *          *  

