Musk's 'AI Day' confronts tough questions about Tesla's technology

SAN FRANCISCO, Aug 18 (Reuters) - At Tesla's "Autonomy Day" event in April 2019, Chief Executive Elon Musk said that by mid-2020 Tesla (TSLA.O) would have over a million self-driving vehicles where riders "could go to sleep" during a trip. Tesla has not achieved that goal and on Thursday Musk is staging another event, called "AI Day," to promote his electric car company as the place to work for the engineers he needs to make good on his promises for autonomous vehicles. Musk has walked back some of his claims for Tesla's "Full Self-Driving" (FSD) system in recent months, saying Tesla cars are "not fully-self driving yet." U.S. safety regulators earlier this week opened an investigation into Tesla's driver assistant system because of accidents where Tesla cars crashed into stationary police cars and fire trucks. "Expectations have been significantly reduced from investors ... Tesla has got some harder questions to answer, what's going on with the safety probe? And how they market FSD?" asked Gene Munster, managing partner at venture capital firm Loup Ventures.