Tesla has cut output of its best-selling Model Y electric car by a double-digit percentage number at its Shanghai plant since March, according to industry data and a source. The move is aimed at addressing weakening demand for the U.S. automaker's aged model in China, its second largest market into which a majority of the cars produced at the Shanghai plant are sold and where a brutal price war has erupted among electric vehicle makers amid an economic slowdown. The Shanghai plant, Tesla's biggest manufacturing hub globally, planned to cut Model Y output by at least 20% during the March to June period, said the person, who declined to be named as the matter is private...