Elon Musk defends embattled autopilot feature in part two of Tesla 'master plan'

• Plans include solar roofs, self-driving buses and merging with SolarCity
• Release comes amid investigation into fatal crash involving self-driving car

Tesla Motors CEO Elon Musk, who is facing intense scrutiny over a fatal crash involving one of his self-driving cars, has released an ambitious new "master plan" and has doubled down on his defense of the safety of the autopilot feature.

Musk's master plan "part deux", published on Wednesday, outlines how he intends to reinvent mass transit systems, integrate "stunning solar roofs" into his cars and build self-driving buses and trucks.