Elon Musk, CEO of Tesla.Antonio Masiello | Getty ImagesTesla shares dropped more than 8% in premarket trading Wednesday in the U.S. after the electric car maker reported second-quarter earnings that missed expectations amid ongoing pressure in its auto business.Elon Musk’s electric vehicle firm on Tuesday announced that automotive revenue declined 7% year on year in the June quarter to $19.9 billion while its adjusted earnings margin also fell.The company has been forced to slash prices globally and offer discounts and incentives amid slowing sales and rising competition, especially in China — one of its key markets.Tesla’s stock is nearly 1% lower this year to date, while the S&P 500 has risen more than 16%.Tesla remains the top seller of electric vehicles in the U.S. by far, but is losing market share to a growing number of rivals due in part to its aging lineup of sedans and SUVs and the impact of Musk’s incendiary and political commentary.Bulls and bears have been in a grapple over the stock, with some believing its core car business is under pressure, while others remain hopeful about a future Musk has promised around autonomous driving, AI and robotaxis.The market has been focused on a number of other areas around the Tesla story, including when the company will introduce a new mass-market car to reinvigorate its lineup of vehicles. Musk said on the earnings call Tuesday that Tesla is on track to deliver a new “affordable” car in the first half of next year.Robotaxis were a huge focus on the earnings call. Musk envisions a world in which owners can authorize their Tesla vehicle to be used as part of an Uber-style ride-hailing service — and where the cars would drive autonomously.When asked when he expects the first robotaxi ride, Musk said, “I would be shocked if we cannot do it next year.”Musk has a history of promising things on a particular timeline and not delivering. On Tuesday, he pushed back the date of the company’s robotaxi event to October, after previously saying it would take place in August.”This is because I wanted to make some important changes that I think would improve the vehicle,” Musk said, adding that Tesla is “going to show up a couple of other things.”Musk did not specify what these items would be.— CNBC’s Lora Kolodny contributed to this report.Don’t miss these insights from CNBC PRO