Tesla's former head of engineering Doug Field is back working with Apple after he took a sudden leave of absence from the Elon Musk firm back in May. In July, it was confirmed the senior engineer would not be returning to Tesla and is instead back with Apple - the company he left five years ago. He will be working on Apple's secretive'Project Titan' autonomous vehicle team, which been running since mid-2016. The two companies have fought over Silicon Valley talent for years with Tesla's CEO Elon Musk once describing Apple's car project as a'Tesla graveyard'. Tesla's former head of engineering Doug Field is back with Apple after first taking a sudden leave of absence back in May.