The longest solar-powered car race came to end yesterday in Claremont, Calif., with a University of Michigan team in the lead. The victorious single-passenger car took 56 hours and 10 minutes to cover 2,247 miles in a 10-day race along Route 66. Twenty-eight teams finished the race, the sixth since the first U.S. competition in 1990 The cars’ price tags range from $30,000 to $1 million, with some of the costs picked up by U.S. automakers and other corporations, though the U.S. Energy Department is the race’s major sponsor.