Musk has good reason to want to reassure mainland drivers. Tesla has big ambitions in the world’s biggest auto market. Doing well here would help the company reach its target of delivering 55,000 vehicles globally in 2015. Musk enjoys rock star adulation in the Chinese press, and there’s no shortage of wealthy consumers who can shell out the $100,000-plus needed to buy a Model S on the mainland.
 However, the luxury electric vehicle maker has had what Musk calls “unexpectedly weak” sales since its launch in the country in April 2014, and worries about running out of juice on longer trips appear to be one reason. China is known for its epic traffic jams, and analysts say “range anxiety” is a challenge for alternative-energy carmakers given the still-developing network of government-mandated charging stations.