Tesla's Autopilot system relies on vision rather than LIDAR, which means it can be tricked by messages on billboards and projections created by hackers.
The billionaire electric car company CEO has previously said the battery event could be "one of the most exciting days in Tesla's history." So what is likely to be revealed?
"If machines drive, and we can make them good at doing that, in the long term it just doesn't make sense that we drive," said Mate Rimac, founder of electric supercar maker Rimac Automobili.
A witness who recorded the video said he called 911 after spotting the driver. Tesla has stressed autopilot is not fully autonomous, describing it as a "driver assistance system."
Former Google engineer Anthony Levandowski allegedly modified cars' software so they could drive on "forbidden" routes.
Most of the specially equipped versions of the Chevrolet Bolt electric vehicle will be used by San Francisco-based Lyft, which will test them in its ride-sharing fleet in several states.