BI senior aviation reporter Taylor Rains saw frontrunner Joby Aviation's eVTOL fly over Manhattan. Taylor Rains/Business Insider Joby Aviation's electric air taxi demo over Manhattan impressed spectators with its futuristic flight. Joby says its eVTOL will cut NYC airport travel time to under 10 minutes with zero emissions. I was there for the flight demonstration. Electric air taxis buzzing over Manhattan are moving from sci-fi fantasy to something much closer to reality. Along the Manhattan waterfront on Friday, a small crowd gathered to watch what would have seemed implausible just a few years ago: a piloted electric flying car lifting off and cruising down the Hudson. The new flying contraptions by US-based Joby Aviation — which has a market value of about $9 billion — have six propellers on top and promise to cut travel time from downtown Manhattan to metro airports like JFK and LaGuardia from more than an hour to fewer than 10 minutes.…