Audi takes a shot at Tesla's Elon Musk in new billboard ad

German automaker Audi has taken a shot at American electric carmaker Tesla's CEO Elon Musk in a billboard posted in Berlin. The hoarding, which advertises the concept of Audi's upcoming electric E-tron Sportback, calls the car a 'Musk-have'. Interestingly, the Audi electric car is not expected to hit the market for at least two years.