A group of disgruntled Tesla Motors Inc. customers in China is protesting delayed deliveries of their cars one day before the electric-vehicle maker is set to make its first China delivery. The furor underscores the challenges facing auto makers in marketing new-energy vehicles in China, which so far hasn’t delivered on the promise of becoming a major new market for electric cars. Tesla’s launch had been heralded as a possible catalyst that could push China farther down the electric-car path. The Palo Alto, Calif., company said in January that it would sell its Model S for $121,000 in China and compete with luxury brands like AG and AG ‘s Audi. Tesla is set on Tuesday to hand over the company’s first Model S to a buyer in China at a high-profile event that is scheduled to feature Tesla Chief Executive . Now, some once-enthused customers like Sam Long are […]