The recession is hitting Orange County, and its residents should prepare to trade in their supercars for something a bit more compact. Lamborghini O.C., the world’s largest Lamborghini dealer, has closed. The dealership previously sold about 10 percent of the 2,400 Lamborghinis made each year. Its owners are refusing to say why they shut their doors. Overall Lamborghini sales are down 15 percent so far this year.