Facing weaker demand in China, Tesla Inc. plans to reduce production at its Shanghai plant by possibly 20% in December, Bloomberg reported on Monday, citing sources. The cuts could kick in this week after the company reviewed the performance of the domestic market, but the sources said output could also be increased again if demand picks up. It marks the first volunteer cut in output by the China plant, which also faces competition from BYD and Guangzhou Automobile. Tesla saw weaker deliveries in October. A Tesla spokesperson did not respond to a Bloomberg request for comment.