Tesla is preparing to release the next version of its Autopilot software, according to a pair of tweets from Tesla CEO Elon Musk. In October, Tesla updated the self-driving hardware in its cars and, since then, buyers of new Teslas have been without the advanced self-driving features of Autopilot because the company was still working on the related software. Musk says the update will roll out to a 1000-car strong test fleet on Monday, with the rest of the Tesla fleet running the update in “shadow mode” where the computer simulates what it would have done if active, and gives Tesla a chance to test the software in more conditions without taking physical control of vehicles.