By Luc Olinga German automaker Mercedes-Benz is building a veritable arsenal to challenge Tesla’s leadership in high-end electric vehicles. Decidedly, Mercedes-Benz is an unstoppable force in the electric-vehicle race. (DDAIF) . The German auto group seems to have decided to make people talk about it. This is an opportunity because Elon Musk, chief executive of EV-market leader Tesla, (TSLA) – Get Tesla Inc Report is currently devoting much of his energy to his $42 billion effort to buy Twitter, (TWTR) – Get Twitter, Inc. Report a proposal that the site’s board is resisting. So Mercedes-Benz h…