US electric carmaker Tesla is sticking to plans to expand its site near Berlin but is leaving the timeline open, according to the manager of the plant, amid protests, production challenges and a difficult market situation. “We firmly believe that the market will pick up again. It is certainly a question of how fast and when,” factory manager André Thierig told dpa. “We won’t invest multiple billions for the factory expansion without clear signals that the market is demanding it.” “We can step on the gas if we realize that we need it,” said Thierig, who has been working in the automotive indust…